refactor Include tag file validation
refactor Include tag file validation

Split validation into a separate method, and give a more
descriptive error on symlinks.

jekyll/jekyll,richsoni/jekyll,egobrightan/jekyll,doubleday/jekyll,tomjohnson1492/jekyll,chinayin/jekyll,rongl/jekyll,AaronSikes/jekyll,garvitr/jekyll,tomjohnson1492/jekyll,vidbina/jekyll,18F/jekyll,chrisfinazzo/jekyll,jaroot32/jekyll,liukaijv/jekyll,floydpraveen/jekyll,matuzo/jekyll,rasa2011/rasa2011.github.io,ryanshaw/jekyll,chinayin/jekyll,howkj1/jekyll,codeclimate-testing/jekyll,derekgottlieb/jekyll,kimeng/jekyll,rovrevik/jekyll,winndows/jekyll,sideci-sample/sideci-sample-jekyll,omeripek/jekyll,MjAbuz/jekyll,naughtyboy83/jekyll,gynter/jekyll,xiaoshaozi52/jekyll,desidude03/jekyll,kinlane/jekyll,garvitr/jekyll,tomjohnson1492/jekyll,PepSalehi/jekyll,rajrathore/jekyll,codeclimate-testing/jekyll,noikiy/jekyll,lazycai/lazycai.github.com,Tiger66639/jekyll,MjAbuz/jekyll,yihangho/jekyll,mrb/jekyll,Tiger66639/jekyll,tomasdiez/jekyll,gynter/jekyll,ewinkler/jekyll,UniFreak/jekyllcn,krahman/jekyll,brint/jekyll,saitodisse/jekyll,ajhit406/jekyll,derekgottlieb/jekyll,AnanthaRajuC/jekyll,digideskio/jekyll,aarvay/jekyll,jekyll/jekyll,digideskio/jekyll,rlugojr/jekyll,hubsaysnuaa/jekyll,ducktyper/jekyll,omeripek/jekyll,brint/jekyll,zhangkuaiji/jekyllcn,honger05/jekyllcn,stomar/jekyll,xcatliu/jekyllcn,rovrevik/jekyll,doubleday/jekyll,AtekiRyu/jekyll,backendeveloper/jekyll,xcatliu/jekyllcn,hartmel/jekyll,nickg33/jekyll,chiyodad/jekyll,indraj/jekyll,garvitr/jekyll,honger05/jekyllcn,adilapapaya/jekyll,derekgottlieb/jekyll,sasongkojati/jekyll,fengsmith/jekyllcn,CorainChicago/jekyll,xantage/jekyll,dangaute/eng,schaazzz/jekyll,jmknoll/jekyll,1gitGrey/jekyll,alfredxing/jekyll,nasht00/jekyll,chrisfinazzo/jekyll,CPVPLachlan/CPVP-Blog,x-way/jekyll,1gitGrey/jekyll,Strangehill/jekyll,matuzo/jekyll,mnuessler/jekyll,vcgato29/jekyll,stevecrozz/jekyll,shliujing/jekyll,tobscure/jekyll,nasht00/jekyll,darwin/jekyll,SQS2/Test,FlyingWHR/jekyll,CPVPLachlan/CPVP-Blog,howkj1/jekyll,AnanthaRajuC/jekyll,m2candre/jekyll,Teino1978-Corp/Teino1978-Corp-jekyll,daniel-beck/jekyll,lcustodio/lcustodio.github.io_base,aarvay/jekyll,richsoni/jekyll,Teino1978-Corp/jekyll,fabulousu/jekyll,pmarsceill/jekyll,LuoPX-15510486969/jekyll,goodtouch/jekyll,UniFreak/jekyllcn,isathish/jekyll,alihalabyah/jekyll,drobati/jekyll,darwin/jekyll,wentixiaogege/jekyll,teju111/jekyll,ramoslin02/jekyll,tillgrallert/jekyll,penchan1218/jekyllcn,isathish/jekyll,PepSalehi/jekyll,cyberid41/jekyll,ReachingOut/jekyll,CPVPLachlan/CPVP-Blog,chinayin/jekyll,alex-kovac/jekyll,tamouse/jekyll,angeliaz/jekyll,supriyantomaftuh/jekyll,daniel-beck/jekyll,jaybe-jekyll/jekyll,jmptrader/jekyll,noikiy/jekyll,egobrightan/jekyll,sferik/jekyll,ducktyper/jekyll,nathanhorrigan1/webdeveloper,Tyrion22/jekyll,getandpost/jekyll.github.io,MjAbuz/jekyll,nateberkopec/jekyll,rongl/jekyll,nathanhorrigan1/webdeveloper,chiyodad/jekyll,johnnycastilho/jekyll,princeofdarkness76/jekyll,yhironaka/yhironaka.github.io,penchan1218/jekyllcn,johnnycastilho/jekyll,jaroot32/jekyll,anthonyrosengren/grasshoppergathering2.github-io,anthonyrosengren/grasshoppergathering2.github-io,AnanthaRajuC/jekyll,tomjohnson1492/jekyll,alfredxing/jekyll,trungvothanh/jekyll,tillgrallert/jekyll,pmarsceill/jekyll,akoeplinger/jekyll,LeuisKen/jekyllcn,schaazzz/jekyll,chiyodad/jekyll,abhilashhb/jekyll,shuber2/jekyll,zsyed91/jekyll,ReachingOut/jekyll,codeclimate-testing/jekyll,FlyingWHR/jekyll,bsmr-ruby/jekyll,xcatliu/jekyllcn,abhilashhb/jekyll,wadaries/jekyll,nemotan/jekyll,kuangyeheng/jekyll,stomar/jekyll,thejameskyle/jekyll,likong/jekyll,jaybe-jekyll/jekyll,Tyrion22/jekyll,digideskio/jekyll,rovrevik/jekyll,lcustodio/lcustodio.github.io_base,rebornix/jekyll,mrb/jekyll,julienbourdeau/jekyll,nickg33/jekyll,hiteshsuthar/jekyll,isathish/jekyll,greent2008/jekyll,CheekyFE/jekyll,nathanhorrigan1/webdeveloper,wentixiaogege/jekyll,xiaoshaozi52/jekyll,krahman/jekyll,QuinntyneBrown/jekyll,MauroMrod/jekyll,ZainRizvi/jekyll,LeuisKen/jekyllcn,wadaries/jekyll,supriyantomaftuh/jekyll,Tiger66639/jekyll,stevecrozz/jekyll,iRoxx/jekyll,ZDroid/jekyll,gencer/jekyll,Wirachmat/jekyll,gencer/jekyll,LuoPX-15510486969/jekyll,liukaijv/jekyll,lazycai/lazycai.github.com,xiebinhqy/jklly_china,akoeplinger/jekyll,harrissoerja/jekyll,naughtyboy83/jekyll,rajrathore/jekyll,PepSalehi/jekyll,sanxore/sanxore.github.com,dezon/jekyll,alihalabyah/jekyll,QuinntyneBrown/jekyll,gkunwar/gkunwar.github.io,jaybe-jekyll/jekyll,brint/jekyll,drobati/jekyll,zhangkuaiji/jekyllcn,jmknoll/jekyll,tillgrallert/jekyll,ReachingOut/jekyll,dansef/jekyll,jmhardison/jekyll,tamouse/jekyll,gencer/jekyll,penchan1218/jekyllcn,desidude03/jekyll,liukaijv/jekyll,ryanshaw/jekyll,julienbourdeau/jekyll,mrb/jekyll,christophermanning/jekyll,leichunxin/jekyll,alex-kovac/jekyll,thetaxman/jekyll,xiebinhqy/jklly_china,nasht00/jekyll,Teino1978-Corp/jekyll,tomasdiez/jekyll,alfredxing/jekyll,adilapapaya/jekyll,Strangehill/jekyll,desidude03/jekyll,jmknoll/jekyll,shuber2/jekyll,mnuessler/jekyll,tobscure/jekyll,jeffkole/jekyll,honger05/jekyllcn,adilapapaya/jekyll,nickg33/jekyll,likong/jekyll,ryanshaw/jekyll,htmelvis/jekyll,jmepg/jekyll,Teino1978-Corp/Teino1978-Corp-jekyll,drobati/jekyll,hubsaysnuaa/jekyll,gkunwar/gkunwar.github.io,rongl/jekyll,x-way/jekyll,EddieDow/jekyll,cyberid41/jekyll,mixxmac/jekyll,gkunwar/gkunwar.github.io,goodtouch/jekyll,oresmus/jekyll,lazycai/lazycai.github.com,ryanshaw/jekyll,eloyesp/jekyll,CheekyFE/jekyll,superve/jekyll,getandpost/jekyll.github.io,stomar/jekyll,larryfox/jekyll,xtymichael/jekyll,getandpost/jekyll.github.io,ajhit406/jekyll,egobrightan/jekyll,Strangehill/jekyll,daniel-beck/jekyll,kuangyeheng/jekyll,ajhit406/jekyll,trungvothanh/jekyll,Teino1978-Corp/jekyll,hartmel/jekyll,tamouse/jekyll,tillgrallert/jekyll,pmarsceill/jekyll,hiteshsuthar/jekyll,zsyed91/jekyll,xtymichael/jekyll,xiebinhqy/jklly_china,gaosboy/jekyll,fengsmith/jekyllcn,alfredxing/jekyll,tylermachen/jekyll,stevecrozz/jekyll,monxim/monxim.github.io,teju111/jekyll,gencer/jekyll,martynbm/jekyll,doubleday/jekyll,ZDroid/jekyll,greent2008/jekyll,zsyed91/jekyll,howkj1/jekyll,jmhardison/jekyll,floydpraveen/jekyll,Teino1978-Corp/Teino1978-Corp-jekyll,EddieDow/jekyll,krishnakalyan3/jekyll,royalwang/jekyll,tareq-s/jekyll,backendeveloper/jekyll,xtymichael/jekyll,gaosboy/jekyll,zsyed91/jekyll,mnuessler/jekyll,fabulousu/jekyll,greent2008/jekyll,fabulousu/jekyll,0x00evil/jekyll,tomjohnson1492/jekyll,vidbina/jekyll,htmelvis/jekyll,bsmr-ruby/jekyll,likong/jekyll,AaronSikes/jekyll,hiteshsuthar/jekyll,marrujoalex/jekyll,floydpraveen/jekyll,foocoder/jekyll,matuzo/jekyll,nasht00/jekyll,Kinghack/kinghack.github.com,winndows/jekyll,ducktyper/jekyll,jaybe-jekyll/jekyll,vcgato29/jekyll,oresmus/jekyll,imaustink/jekyll,shliujing/jekyll,CorainChicago/jekyll,fengsmith/jekyll,EddieDow/jekyll,jeffkole/jekyll,superve/jekyll,xantage/jekyll,dezon/jekyll,tobscure/jekyll,teju111/jekyll,saitodisse/jekyll,princeofdarkness76/jekyll,stomar/jekyll,sasongkojati/jekyll,rasa2011/rasa2011.github.io,rebornix/jekyll,jmhardison/jekyll,johnnycastilho/jekyll,harrissoerja/jekyll,xiongjungit/jekyll,princeofdarkness76/jekyll,noikiy/jekyll,m2candre/jekyll,ewinkler/jekyll,AtekiRyu/jekyll,ls2uper/jekyll,imaustink/jekyll,fengsmith/jekyll,ramoslin02/jekyll,goragod/jekyll,FlyingWHR/jekyll,alex-kovac/jekyll,brint/jekyll,nateberkopec/jekyll,dansef/jekyll,kimeng/jekyll,SQS2/Test,indraj/jekyll,leichunxin/jekyll,dezon/jekyll,omeripek/jekyll,Wirachmat/jekyll,goragod/jekyll,indraj/jekyll,AaronSikes/jekyll,lcustodio/lcustodio.github.io_base,darwin/jekyll,sanxore/sanxore.github.com,oresmus/jekyll,marrujoalex/jekyll,18F/jekyll,tareq-s/jekyll,pheuko/jekyll,kuangyeheng/jekyll,LeuisKen/jekyllcn,christophermanning/jekyll,tylermachen/jekyll,tillgrallert/jekyll,pheuko/jekyll,dansef/jekyll,Wirachmat/jekyll,Tyrion22/jekyll,pmarsceill/jekyll,Strangehill/jekyll,MauroMrod/jekyll,wadaries/jekyll,fulldecent/jekyll,ZainRizvi/jekyll,chrisfinazzo/jekyll,richsoni/jekyll,ajhit406/jekyll,floydpraveen/jekyll,hubsaysnuaa/jekyll,goragod/jekyll,AtekiRyu/jekyll,alex-kovac/jekyll,kinlane/jekyll,ZainRizvi/jekyll,dangaute/eng,jmepg/jekyll,yihangho/jekyll,htmelvis/jekyll,gynter/jekyll,sanxore/sanxore.github.com,thetaxman/jekyll,monxim/monxim.github.io,rlugojr/jekyll,krishnakalyan3/jekyll,vidbina/jekyll,jmepg/jekyll,foocoder/jekyll,mixxmac/jekyll,shliujing/jekyll,UniFreak/jekyllcn,shuber2/jekyll,tugberkugurlu/jekyll,xiongjungit/jekyll,Kinghack/kinghack.github.com,harrissoerja/jekyll,jmptrader/jekyll,xiaoshaozi52/jekyll,tugberkugurlu/jekyll,xiebinhqy/jklly_china,iRoxx/jekyll,fulldecent/jekyll,tugberkugurlu/jekyll,trungvothanh/jekyll,yihangho/jekyll,backendeveloper/jekyll,chrisfinazzo/jekyll,rlugojr/jekyll,LuoPX-15510486969/jekyll,leichunxin/jekyll,lazycai/lazycai.github.com,0x00evil/jekyll,darwin/jekyll,eloyesp/jekyll,CorainChicago/jekyll,sasongkojati/jekyll,thetaxman/jekyll,aarvay/jekyll,eninya/jekyll,ewinkler/jekyll,fengsmith/jekyllcn,mixxmac/jekyll,winndows/jekyll,martynbm/jekyll,bsmr-ruby/jekyll,pheuko/jekyll,jekyll/jekyll,CheekyFE/jekyll,wentixiaogege/jekyll,abhilashhb/jekyll,0x00evil/jekyll,christophermanning/jekyll,xantage/jekyll,jeffkole/jekyll,fulldecent/jekyll,ls2uper/jekyll,mrb/jekyll,xcatliu/jekyllcn,Kinghack/kinghack.github.com,marrujoalex/jekyll,vcgato29/jekyll,alex-kovac/jekyll,thejameskyle/jekyll,princeofdarkness76/jekyll,m2candre/jekyll,jekyll/jekyll,krahman/jekyll,jeffkole/jekyll,anthonyrosengren/grasshoppergathering2.github-io,dangaute/eng,nateberkopec/jekyll,nemotan/jekyll,eninya/jekyll,noikiy/jekyll,schaazzz/jekyll,x-way/jekyll,supriyantomaftuh/jekyll,gaosboy/jekyll,julienbourdeau/jekyll,Strangehill/jekyll,angeliaz/jekyll,saitodisse/jekyll,sferik/jekyll,bsmr-ruby/jekyll,cyberid41/jekyll,x-way/jekyll,fengsmith/jekyll,royalwang/jekyll,thejameskyle/jekyll,alihalabyah/jekyll,xiongjungit/jekyll,hartmel/jekyll,eninya/jekyll,ls2uper/jekyll,18F/jekyll,gencer/jekyll,rlugojr/jekyll,zhangkuaiji/jekyllcn,tylermachen/jekyll,imaustink/jekyll,nemotan/jekyll,larryfox/jekyll,derekgottlieb/jekyll,iRoxx/jekyll,rasa2011/rasa2011.github.io,kimeng/jekyll,QuinntyneBrown/jekyll,foocoder/jekyll,rajrathore/jekyll,naughtyboy83/jekyll,tomasdiez/jekyll,sideci-sample/sideci-sample-jekyll,MauroMrod/jekyll,jaroot32/jekyll,larryfox/jekyll,SQS2/Test,tareq-s/jekyll,ZDroid/jekyll,rebornix/jekyll,martynbm/jekyll,royalwang/jekyll,superve/jekyll,jmptrader/jekyll,fulldecent/jekyll,angeliaz/jekyll,ramoslin02/jekyll,eloyesp/jekyll,krishnakalyan3/jekyll