Add unit tests for Registry#keys.
Add unit tests for Registry#keys.

clinstid/vagrant,bshurts/vagrant,bheuvel/vagrant,vamegh/vagrant,tschortsch/vagrant,senglin/vagrant,doy/vagrant,muhanadra/vagrant,philwrenn/vagrant,teotihuacanada/vagrant,wangfakang/vagrant,dhoer/vagrant,apertoso/vagrant,modulexcite/vagrant,dharmab/vagrant,patrys/vagrant,mpoeter/vagrant,vamegh/vagrant,chrisroberts/vagrant,Endika/vagrant,chrisvire/vagrant,gbarberi/vagrant,tjanez/vagrant,Sgoettschkes/vagrant,Chhunlong/vagrant,denisbr/vagrant,janek-warchol/vagrant,mpoeter/vagrant,taliesins/vagrant,philwrenn/vagrant,bdwyertech/vagrant,mwarren/vagrant,kamigerami/vagrant,gitebra/vagrant,denisbr/vagrant,gitebra/vagrant,clinstid/vagrant,wangfakang/vagrant,PatOShea/vagrant,mkuzmin/vagrant,chrisvire/vagrant,lonniev/vagrant,teotihuacanada/vagrant,kalabiyau/vagrant,rivy/vagrant,TheBigBear/vagrant,mitchellh/vagrant,loren-osborn/vagrant,johntron/vagrant,aaam/vagrant,jfchevrette/vagrant,chrisvire/vagrant,carlosefr/vagrant,jkburges/vagrant,doy/vagrant,teotihuacanada/vagrant,h4ck3rm1k3/vagrant,zsjohny/vagrant,ianmiell/vagrant,dhoer/vagrant,signed8bit/vagrant,wangfakang/vagrant,gpkfr/vagrant,Avira/vagrant,ArloL/vagrant,marxarelli/vagrant,gpkfr/vagrant,obnoxxx/vagrant,cgvarela/vagrant,kamigerami/vagrant,wkolean/vagrant,aneeshusa/vagrant,tbarrongh/vagrant,gbarberi/vagrant,marxarelli/vagrant,kamazee/vagrant,petems/vagrant,stephancom/vagrant,carlosefr/vagrant,kamazee/vagrant,shtouff/vagrant,jmanero/vagrant,MiLk/vagrant,PatOShea/vagrant,PatrickLang/vagrant,denisbr/vagrant,h4ck3rm1k3/vagrant,jmanero/vagrant,tbriggs-curse/vagrant,myrjola/vagrant,marxarelli/vagrant,jberends/vagrant,benh57/vagrant,Avira/vagrant,vamegh/vagrant,philoserf/vagrant,dharmab/vagrant,johntron/vagrant,TheBigBear/vagrant,mkuzmin/vagrant,jfchevrette/vagrant,aneeshusa/vagrant,Chhunlong/vagrant,benizi/vagrant,rivy/vagrant,tschortsch/vagrant,taliesins/vagrant,Endika/vagrant,genome21/vagrant,miguel250/vagrant,tbarrongh/vagrant,ArloL/vagrant,patrys/vagrant,Sgoettschkes/vagrant,tomfanning/vagrant,dhoer/vagrant,stephancom/vagrant,MiLk/vagrant,juiceinc/vagrant,TheBigBear/vagrant,MiLk/vagrant,PatrickLang/vagrant,jean/vagrant,darkn3rd/vagrant,blueyed/vagrant,ArloL/vagrant,Avira/vagrant,fnewberg/vagrant,legal90/vagrant,myrjola/vagrant,benizi/vagrant,benizi/vagrant,jtopper/vagrant,PatOShea/vagrant,benh57/vagrant,obnoxxx/vagrant,sideci-sample/sideci-sample-vagrant,bryson/vagrant,lonniev/vagrant,lukebakken/vagrant,myrjola/vagrant,bdwyertech/vagrant,lukebakken/vagrant,blueyed/vagrant,jtopper/vagrant,gajdaw/vagrant,p0deje/vagrant,krig/vagrant,tschortsch/vagrant,janek-warchol/vagrant,invernizzi-at-google/vagrant,jhoblitt/vagrant,mwrock/vagrant,mwarren/vagrant,justincampbell/vagrant,jfchevrette/vagrant,bryson/vagrant,ferventcoder/vagrant,loren-osborn/vagrant,jmanero/vagrant,muhanadra/vagrant,ianmiell/vagrant,gajdaw/vagrant,Endika/vagrant,Chhunlong/vagrant,dhoer/vagrant,gbarberi/vagrant,darkn3rd/vagrant,BlakeMesdag/vagrant,johntron/vagrant,jkburges/vagrant,bshurts/vagrant,sni/vagrant,bheuvel/vagrant,doy/vagrant,kamazee/vagrant,tbriggs-curse/vagrant,fnewberg/vagrant,jfchevrette/vagrant,rivy/vagrant,channui/vagrant,mitchellh/vagrant,bshurts/vagrant,taliesins/vagrant,otagi/vagrant,petems/vagrant,justincampbell/vagrant,sax/vagrant,juiceinc/vagrant,gbarberi/vagrant,dustymabe/vagrant,ianmiell/vagrant,rivy/vagrant,wkolean/vagrant,lukebakken/vagrant,nickryand/vagrant,tbriggs-curse/vagrant,senglin/vagrant,chrisroberts/vagrant,mwrock/vagrant,cgvarela/vagrant,modulexcite/vagrant,p0deje/vagrant,clinstid/vagrant,jean/vagrant,sni/vagrant,jmanero/vagrant,taliesins/vagrant,senglin/vagrant,apertoso/vagrant,shtouff/vagrant,wkolean/vagrant,loren-osborn/vagrant,sax/vagrant,jtopper/vagrant,juiceinc/vagrant,jean/vagrant,obnoxxx/vagrant,zsjohny/vagrant,wkolean/vagrant,tknerr/vagrant,sni/vagrant,bryson/vagrant,otagi/vagrant,tknerr/vagrant,tomfanning/vagrant,blueyed/vagrant,bryson/vagrant,loren-osborn/vagrant,crashlytics/vagrant,Chhed13/vagrant,BlakeMesdag/vagrant,dustymabe/vagrant,Endika/vagrant,theist/vagrant,tbarrongh/vagrant,otagi/vagrant,tknerr/vagrant,patrys/vagrant,philoserf/vagrant,muhanadra/vagrant,mwarren/vagrant,ferventcoder/vagrant,sideci-sample/sideci-sample-vagrant,denisbr/vagrant,marxarelli/vagrant,iNecas/vagrant,jhoblitt/vagrant,signed8bit/vagrant,carlosefr/vagrant,benh57/vagrant,mkuzmin/vagrant,johntron/vagrant,benizi/vagrant,mitchellh/vagrant,Sgoettschkes/vagrant,krig/vagrant,kalabiyau/vagrant,h4ck3rm1k3/vagrant,Chhed13/vagrant,p0deje/vagrant,Avira/vagrant,tbriggs-curse/vagrant,chrisroberts/vagrant,pwnall/vagrant,cgvarela/vagrant,gpkfr/vagrant,sax/vagrant,aaam/vagrant,sni/vagrant,philwrenn/vagrant,ferventcoder/vagrant,chrisvire/vagrant,invernizzi-at-google/vagrant,Chhunlong/vagrant,bdwyertech/vagrant,legal90/vagrant,lonniev/vagrant,theist/vagrant,nickryand/vagrant,jkburges/vagrant,carlosefr/vagrant,jean/vagrant,pwnall/vagrant,zsjohny/vagrant,lukebakken/vagrant,tomfanning/vagrant,theist/vagrant,tjanez/vagrant,evverx/vagrant,fnewberg/vagrant,apertoso/vagrant,petems/vagrant,gitebra/vagrant,modulexcite/vagrant,zsjohny/vagrant,benh57/vagrant,miguel250/vagrant,channui/vagrant,genome21/vagrant,fnewberg/vagrant,modulexcite/vagrant,dustymabe/vagrant,philwrenn/vagrant,muhanadra/vagrant,wangfakang/vagrant,patrys/vagrant,tjanez/vagrant,krig/vagrant,miguel250/vagrant,shtouff/vagrant,justincampbell/vagrant,h4ck3rm1k3/vagrant,apertoso/vagrant,kamigerami/vagrant,ianmiell/vagrant,genome21/vagrant,iNecas/vagrant,vamegh/vagrant,miguel250/vagrant,mwrock/vagrant,aneeshusa/vagrant,tschortsch/vagrant,ferventcoder/vagrant,aneeshusa/vagrant,legal90/vagrant,philoserf/vagrant,jberends/vagrant,nickryand/vagrant,PatrickLang/vagrant,darkn3rd/vagrant,petems/vagrant,Chhed13/vagrant,PatrickLang/vagrant,stephancom/vagrant,jhoblitt/vagrant,crashlytics/vagrant,bheuvel/vagrant,theist/vagrant,aaam/vagrant,iNecas/vagrant,jkburges/vagrant,kamazee/vagrant,ArloL/vagrant,pwnall/vagrant,stephancom/vagrant,sax/vagrant,crashlytics/vagrant,BlakeMesdag/vagrant,legal90/vagrant,janek-warchol/vagrant,invernizzi-at-google/vagrant,kalabiyau/vagrant,krig/vagrant,gajdaw/vagrant,jberends/vagrant,mkuzmin/vagrant,evverx/vagrant,myrjola/vagrant,mwrock/vagrant,dharmab/vagrant,philoserf/vagrant,invernizzi-at-google/vagrant,pwnall/vagrant,nickryand/vagrant,jhoblitt/vagrant,shtouff/vagrant,crashlytics/vagrant,gitebra/vagrant,tomfanning/vagrant,doy/vagrant,teotihuacanada/vagrant,blueyed/vagrant,channui/vagrant,lonniev/vagrant,kamigerami/vagrant,mpoeter/vagrant,evverx/vagrant,genome21/vagrant,dustymabe/vagrant,aaam/vagrant,Chhed13/vagrant,cgvarela/vagrant,janek-warchol/vagrant,signed8bit/vagrant,darkn3rd/vagrant,mpoeter/vagrant,jtopper/vagrant,signed8bit/vagrant,chrisroberts/vagrant,mwarren/vagrant,gpkfr/vagrant,mitchellh/vagrant,TheBigBear/vagrant,PatOShea/vagrant,otagi/vagrant,justincampbell/vagrant,kalabiyau/vagrant,senglin/vagrant,juiceinc/vagrant,tjanez/vagrant,bshurts/vagrant,tknerr/vagrant,sideci-sample/sideci-sample-vagrant,dharmab/vagrant,Sgoettschkes/vagrant,bheuvel/vagrant,jberends/vagrant,tbarrongh/vagrant,bdwyertech/vagrant