Fix NuGet.exe package restore on systems where wget fails because of missing CA-trust.
Fix NuGet.exe package restore on systems where wget fails because of missing CA-trust.

Trying to run `build.sh` on a clean FreeBSD-system will fail because NuGet.exe isn't downloaded
correctly.

````
/usr/home/josteink/build/corefx $ wget https://api.nuget.org/downloads/nuget.exe
--2015-06-21 05:43:58-- https://api.nuget.org/downloads/nuget.exe
Resolving api.nuget.org (api.nuget.org)...
185.31.18.64 Connecting to api.nuget.org (api.nuget.org)|185.31.18.64|:443... connected.
ERROR: cannot verify api.nuget.org's certificate, issued by ‘CN=DigiCert SHA2 High Assurance Server CA,OU=www.digicert.com,O=DigiCert Inc,C=US’:
 Unable to locally verify the issuer's authority.
To connect to api.nuget.org insecurely, use `--no-check-certificate'.
/usr/home/josteink/build/corefx $
````

This is the case on a default FreeBSD 10.1 installation, and the same behaviour
with wget failing on HTTPS trust-issues can very often be observed in the wild
across several OSes and projects, not just FreeBSD and corefx.

(For FreeBSD, a workaround for this issue is to install the `/usr/ports/security/ca_root_nss`,
but this package is not installed by default.)

After this error has (silently) happened, a zero-byte NuGet.exe is left on disk, causing
all subsequent builds to fail on the MSbuild-restore stage.

Downloading with curl however doesn't fail, so default to trying curl instead of wget first
solves this issue.

shana/corefx,jlin177/corefx,Frank125/corefx,ViktorHofer/corefx,YoupHulsebos/corefx,anjumrizwi/corefx,gabrielPeart/corefx,adamralph/corefx,bpschoch/corefx,pallavit/corefx,jlin177/corefx,benpye/corefx,Jiayili1/corefx,Frank125/corefx,DnlHarvey/corefx,MaggieTsang/corefx,seanshpark/corefx,anjumrizwi/corefx,gabrielPeart/corefx,rubo/corefx,Chrisboh/corefx,Petermarcu/corefx,alexperovich/corefx,janhenke/corefx,YoupHulsebos/corefx,cnbin/corefx,heXelium/corefx,jcme/corefx,seanshpark/corefx,huanjie/corefx,dhoehna/corefx,vidhya-bv/corefx-sorting,shimingsg/corefx,gregg-miskelly/corefx,ptoonen/corefx,alphonsekurian/corefx,CloudLens/corefx,mokchhya/corefx,jlin177/corefx,parjong/corefx,stormleoxia/corefx,Ermiar/corefx,twsouthwick/corefx,destinyclown/corefx,cartermp/corefx,shahid-pk/corefx,nchikanov/corefx,pgavlin/corefx,stormleoxia/corefx,twsouthwick/corefx,ericstj/corefx,cartermp/corefx,Petermarcu/corefx,iamjasonp/corefx,lggomez/corefx,chenxizhang/corefx,Ermiar/corefx,SGuyGe/corefx,690486439/corefx,Petermarcu/corefx,mafiya69/corefx,mokchhya/corefx,rahku/corefx,cydhaselton/corefx,mmitche/corefx,Priya91/corefx-1,scott156/corefx,shana/corefx,CherryCxldn/corefx,viniciustaveira/corefx,Priya91/corefx-1,richlander/corefx,zmaruo/corefx,ellismg/corefx,kyulee1/corefx,pgavlin/corefx,alphonsekurian/corefx,nbarbettini/corefx,dotnet-bot/corefx,claudelee/corefx,mmitche/corefx,JosephTremoulet/corefx,oceanho/corefx,weltkante/corefx,Priya91/corefx-1,fffej/corefx,jhendrixMSFT/corefx,heXelium/corefx,parjong/corefx,krytarowski/corefx,akivafr123/corefx,elijah6/corefx,Priya91/corefx-1,Yanjing123/corefx,alexperovich/corefx,dotnet-bot/corefx,zhangwenquan/corefx,DnlHarvey/corefx,mafiya69/corefx,axelheer/corefx,dtrebbien/corefx,Winsto/corefx,mmitche/corefx,misterzik/corefx,gkhanna79/corefx,jeremymeng/corefx,nchikanov/corefx,mellinoe/corefx,jhendrixMSFT/corefx,wtgodbe/corefx,tijoytom/corefx,cydhaselton/corefx,the-dwyer/corefx,yizhang82/corefx,krytarowski/corefx,ravimeda/corefx,billwert/corefx,jmhardison/corefx,zhenlan/corefx,thiagodin/corefx,rjxby/corefx,KrisLee/corefx,fgreinacher/corefx,iamjasonp/corefx,ViktorHofer/corefx,nelsonsar/corefx,Yanjing123/corefx,s0ne0me/corefx,billwert/corefx,ViktorHofer/corefx,zmaruo/corefx,misterzik/corefx,twsouthwick/corefx,stephenmichaelf/corefx,alphonsekurian/corefx,nchikanov/corefx,josguil/corefx,manu-silicon/corefx,rahku/corefx,stephenmichaelf/corefx,zhenlan/corefx,tijoytom/corefx,s0ne0me/corefx,elijah6/corefx,matthubin/corefx,destinyclown/corefx,mellinoe/corefx,rjxby/corefx,mmitche/corefx,jcme/corefx,manu-silicon/corefx,cydhaselton/corefx,dotnet-bot/corefx,fffej/corefx,ravimeda/corefx,jcme/corefx,ptoonen/corefx,Petermarcu/corefx,jhendrixMSFT/corefx,benjamin-bader/corefx,brett25/corefx,alexperovich/corefx,elijah6/corefx,CloudLens/corefx,axelheer/corefx,MaggieTsang/corefx,SGuyGe/corefx,PatrickMcDonald/corefx,anjumrizwi/corefx,fgreinacher/corefx,gkhanna79/corefx,alexperovich/corefx,gkhanna79/corefx,bpschoch/corefx,rjxby/corefx,fernando-rodriguez/corefx,dotnet-bot/corefx,scott156/corefx,Alcaro/corefx,krk/corefx,mazong1123/corefx,SGuyGe/corefx,PatrickMcDonald/corefx,comdiv/corefx,s0ne0me/corefx,mafiya69/corefx,ravimeda/corefx,wtgodbe/corefx,CherryCxldn/corefx,BrennanConroy/corefx,690486439/corefx,jhendrixMSFT/corefx,elijah6/corefx,rjxby/corefx,benpye/corefx,stone-li/corefx,cnbin/corefx,krk/corefx,yizhang82/corefx,yizhang82/corefx,popolan1986/corefx,larsbj1988/corefx,yizhang82/corefx,mellinoe/corefx,janhenke/corefx,mellinoe/corefx,josguil/corefx,rajansingh10/corefx,n1ghtmare/corefx,vrassouli/corefx,VPashkov/corefx,Frank125/corefx,axelheer/corefx,richlander/corefx,akivafr123/corefx,krk/corefx,ericstj/corefx,billwert/corefx,nchikanov/corefx,kkurni/corefx,billwert/corefx,shmao/corefx,uhaciogullari/corefx,claudelee/corefx,axelheer/corefx,rahku/corefx,rahku/corefx,EverlessDrop41/corefx,Jiayili1/corefx,690486439/corefx,thiagodin/corefx,VPashkov/corefx,JosephTremoulet/corefx,andyhebear/corefx,lggomez/corefx,bitcrazed/corefx,690486439/corefx,dtrebbien/corefx,dhoehna/corefx,rubo/corefx,YoupHulsebos/corefx,SGuyGe/corefx,alexperovich/corefx,EverlessDrop41/corefx,iamjasonp/corefx,richlander/corefx,ptoonen/corefx,khdang/corefx,parjong/corefx,alexandrnikitin/corefx,rubo/corefx,comdiv/corefx,shmao/corefx,oceanho/corefx,pallavit/corefx,Priya91/corefx-1,PatrickMcDonald/corefx,khdang/corefx,iamjasonp/corefx,stephenmichaelf/corefx,dhoehna/corefx,JosephTremoulet/corefx,dtrebbien/corefx,Jiayili1/corefx,zhangwenquan/corefx,tijoytom/corefx,tstringer/corefx,Jiayili1/corefx,Petermarcu/corefx,ellismg/corefx,billwert/corefx,tstringer/corefx,fgreinacher/corefx,nelsonsar/corefx,zhenlan/corefx,lggomez/corefx,ptoonen/corefx,vrassouli/corefx,rajansingh10/corefx,lggomez/corefx,heXelium/corefx,manu-silicon/corefx,twsouthwick/corefx,josguil/corefx,chaitrakeshav/corefx,shmao/corefx,akivafr123/corefx,andyhebear/corefx,andyhebear/corefx,bitcrazed/corefx,Chrisboh/corefx,MaggieTsang/corefx,billwert/corefx,zhenlan/corefx,stephenmichaelf/corefx,rubo/corefx,gabrielPeart/corefx,mazong1123/corefx,josguil/corefx,claudelee/corefx,elijah6/corefx,Winsto/corefx,axelheer/corefx,mokchhya/corefx,shrutigarg/corefx,seanshpark/corefx,janhenke/corefx,BrennanConroy/corefx,zhangwenquan/corefx,wtgodbe/corefx,krk/corefx,twsouthwick/corefx,nbarbettini/corefx,Ermiar/corefx,fernando-rodriguez/corefx,JosephTremoulet/corefx,ravimeda/corefx,pallavit/corefx,rjxby/corefx,dhoehna/corefx,Alcaro/corefx,viniciustaveira/corefx,parjong/corefx,DnlHarvey/corefx,Priya91/corefx-1,YoupHulsebos/corefx,vrassouli/corefx,fffej/corefx,richlander/corefx,ericstj/corefx,the-dwyer/corefx,bpschoch/corefx,stone-li/corefx,YoupHulsebos/corefx,fgreinacher/corefx,janhenke/corefx,alphonsekurian/corefx,weltkante/corefx,misterzik/corefx,Ermiar/corefx,Yanjing123/corefx,dhoehna/corefx,jeremymeng/corefx,stephenmichaelf/corefx,shimingsg/corefx,mazong1123/corefx,VPashkov/corefx,rahku/corefx,JosephTremoulet/corefx,rjxby/corefx,matthubin/corefx,xuweixuwei/corefx,stone-li/corefx,krytarowski/corefx,mafiya69/corefx,marksmeltzer/corefx,richlander/corefx,lydonchandra/corefx,yizhang82/corefx,akivafr123/corefx,Alcaro/corefx,cydhaselton/corefx,matthubin/corefx,nbarbettini/corefx,jlin177/corefx,zhenlan/corefx,SGuyGe/corefx,wtgodbe/corefx,vidhya-bv/corefx-sorting,Ermiar/corefx,mellinoe/corefx,gkhanna79/corefx,CloudLens/corefx,Ermiar/corefx,nchikanov/corefx,vijaykota/corefx,BrennanConroy/corefx,benjamin-bader/corefx,khdang/corefx,nbarbettini/corefx,oceanho/corefx,CherryCxldn/corefx,alphonsekurian/corefx,shimingsg/corefx,brett25/corefx,dkorolev/corefx,gkhanna79/corefx,nbarbettini/corefx,tijoytom/corefx,cartermp/corefx,huanjie/corefx,khdang/corefx,pallavit/corefx,marksmeltzer/corefx,chaitrakeshav/corefx,huanjie/corefx,n1ghtmare/corefx,dsplaisted/corefx,gregg-miskelly/corefx,mmitche/corefx,ravimeda/corefx,lydonchandra/corefx,vs-team/corefx,Petermarcu/corefx,pgavlin/corefx,the-dwyer/corefx,adamralph/corefx,Chrisboh/corefx,Alcaro/corefx,zhangwenquan/corefx,DnlHarvey/corefx,lggomez/corefx,Frank125/corefx,tijoytom/corefx,xuweixuwei/corefx,wtgodbe/corefx,jeremymeng/corefx,CherryCxldn/corefx,ellismg/corefx,chenxizhang/corefx,fernando-rodriguez/corefx,benpye/corefx,weltkante/corefx,thiagodin/corefx,jlin177/corefx,marksmeltzer/corefx,weltkante/corefx,jcme/corefx,stone-li/corefx,cartermp/corefx,cnbin/corefx,cnbin/corefx,dsplaisted/corefx,dsplaisted/corefx,twsouthwick/corefx,mokchhya/corefx,shahid-pk/corefx,YoupHulsebos/corefx,tijoytom/corefx,vidhya-bv/corefx-sorting,krk/corefx,vidhya-bv/corefx-sorting,ellismg/corefx,erpframework/corefx,mokchhya/corefx,cydhaselton/corefx,nchikanov/corefx,cydhaselton/corefx,shahid-pk/corefx,ptoonen/corefx,bitcrazed/corefx,andyhebear/corefx,dkorolev/corefx,mazong1123/corefx,brett25/corefx,n1ghtmare/corefx,manu-silicon/corefx,heXelium/corefx,tstringer/corefx,shmao/corefx,kyulee1/corefx,wtgodbe/corefx,jmhardison/corefx,tstringer/corefx,Jiayili1/corefx,Jiayili1/corefx,marksmeltzer/corefx,nbarbettini/corefx,scott156/corefx,shrutigarg/corefx,KrisLee/corefx,jeremymeng/corefx,billwert/corefx,Chrisboh/corefx,n1ghtmare/corefx,the-dwyer/corefx,shana/corefx,huanjie/corefx,kkurni/corefx,mmitche/corefx,shahid-pk/corefx,ericstj/corefx,jeremymeng/corefx,weltkante/corefx,VPashkov/corefx,shrutigarg/corefx,benjamin-bader/corefx,zhenlan/corefx,elijah6/corefx,zmaruo/corefx,dotnet-bot/corefx,larsbj1988/corefx,josguil/corefx,adamralph/corefx,rjxby/corefx,alexandrnikitin/corefx,benjamin-bader/corefx,yizhang82/corefx,the-dwyer/corefx,mellinoe/corefx,popolan1986/corefx,bitcrazed/corefx,janhenke/corefx,thiagodin/corefx,stone-li/corefx,ViktorHofer/corefx,mokchhya/corefx,krytarowski/corefx,benjamin-bader/corefx,dhoehna/corefx,CloudLens/corefx,MaggieTsang/corefx,benpye/corefx,dkorolev/corefx,axelheer/corefx,dtrebbien/corefx,larsbj1988/corefx,ravimeda/corefx,gregg-miskelly/corefx,jcme/corefx,s0ne0me/corefx,shimingsg/corefx,kyulee1/corefx,marksmeltzer/corefx,stormleoxia/corefx,matthubin/corefx,DnlHarvey/corefx,cydhaselton/corefx,ellismg/corefx,cartermp/corefx,uhaciogullari/corefx,elijah6/corefx,richlander/corefx,stone-li/corefx,ptoonen/corefx,zhenlan/corefx,vijaykota/corefx,krk/corefx,jlin177/corefx,MaggieTsang/corefx,PatrickMcDonald/corefx,kkurni/corefx,gkhanna79/corefx,krk/corefx,nelsonsar/corefx,Chrisboh/corefx,jhendrixMSFT/corefx,weltkante/corefx,erpframework/corefx,wtgodbe/corefx,vidhya-bv/corefx-sorting,dotnet-bot/corefx,benjamin-bader/corefx,ViktorHofer/corefx,stephenmichaelf/corefx,ViktorHofer/corefx,mazong1123/corefx,krytarowski/corefx,krytarowski/corefx,Jiayili1/corefx,rajansingh10/corefx,jmhardison/corefx,seanshpark/corefx,weltkante/corefx,alexperovich/corefx,chenxizhang/corefx,MaggieTsang/corefx,richlander/corefx,twsouthwick/corefx,seanshpark/corefx,janhenke/corefx,mmitche/corefx,benpye/corefx,comdiv/corefx,claudelee/corefx,ptoonen/corefx,pallavit/corefx,jhendrixMSFT/corefx,rahku/corefx,YoupHulsebos/corefx,josguil/corefx,ViktorHofer/corefx,manu-silicon/corefx,iamjasonp/corefx,cartermp/corefx,parjong/corefx,bitcrazed/corefx,shmao/corefx,viniciustaveira/corefx,ellismg/corefx,ravimeda/corefx,n1ghtmare/corefx,vrassouli/corefx,DnlHarvey/corefx,chenkennt/corefx,nbarbettini/corefx,destinyclown/corefx,marksmeltzer/corefx,erpframework/corefx,jcme/corefx,shana/corefx,Chrisboh/corefx,lydonchandra/corefx,ericstj/corefx,pallavit/corefx,rahku/corefx,chaitrakeshav/corefx,PatrickMcDonald/corefx,manu-silicon/corefx,alexandrnikitin/corefx,lggomez/corefx,kkurni/corefx,erpframework/corefx,vs-team/corefx,mafiya69/corefx,shimingsg/corefx,nchikanov/corefx,shrutigarg/corefx,Petermarcu/corefx,EverlessDrop41/corefx,shmao/corefx,alexandrnikitin/corefx,Yanjing123/corefx,shmao/corefx,rajansingh10/corefx,kkurni/corefx,mazong1123/corefx,shimingsg/corefx,nelsonsar/corefx,ericstj/corefx,mafiya69/corefx,jhendrixMSFT/corefx,dhoehna/corefx,lydonchandra/corefx,anjumrizwi/corefx,DnlHarvey/corefx,pgavlin/corefx,lggomez/corefx,SGuyGe/corefx,stormleoxia/corefx,JosephTremoulet/corefx,iamjasonp/corefx,khdang/corefx,dotnet-bot/corefx,Ermiar/corefx,alexandrnikitin/corefx,ericstj/corefx,JosephTremoulet/corefx,gabrielPeart/corefx,kyulee1/corefx,mazong1123/corefx,shahid-pk/corefx,Yanjing123/corefx,fffej/corefx,690486439/corefx,iamjasonp/corefx,gkhanna79/corefx,gregg-miskelly/corefx,shahid-pk/corefx,KrisLee/corefx,manu-silicon/corefx,popolan1986/corefx,krytarowski/corefx,KrisLee/corefx,chenkennt/corefx,zmaruo/corefx,viniciustaveira/corefx,tijoytom/corefx,the-dwyer/corefx,seanshpark/corefx,parjong/corefx,chenkennt/corefx,scott156/corefx,alexperovich/corefx,tstringer/corefx,larsbj1988/corefx,the-dwyer/corefx,uhaciogullari/corefx,vs-team/corefx,akivafr123/corefx,alphonsekurian/corefx,shimingsg/corefx,alphonsekurian/corefx,yizhang82/corefx,MaggieTsang/corefx,comdiv/corefx,dkorolev/corefx,stone-li/corefx,xuweixuwei/corefx,jmhardison/corefx,marksmeltzer/corefx,oceanho/corefx,vs-team/corefx,vijaykota/corefx,parjong/corefx,jlin177/corefx,seanshpark/corefx,benpye/corefx,brett25/corefx,uhaciogullari/corefx,Winsto/corefx,khdang/corefx,bpschoch/corefx,kkurni/corefx,tstringer/corefx,chaitrakeshav/corefx,rubo/corefx,stephenmichaelf/corefx