Bump 15.9.x to -beta2 version
Bump 15.9.x to -beta2 version

mavasani/roslyn,jasonmalinowski/roslyn,VSadov/roslyn,KirillOsenkov/roslyn,dpoeschl/roslyn,gafter/roslyn,panopticoncentral/roslyn,nguerrera/roslyn,cston/roslyn,cston/roslyn,panopticoncentral/roslyn,swaroop-sridhar/roslyn,weltkante/roslyn,DustinCampbell/roslyn,CyrusNajmabadi/roslyn,KevinRansom/roslyn,agocke/roslyn,MichalStrehovsky/roslyn,diryboy/roslyn,eriawan/roslyn,DustinCampbell/roslyn,tmat/roslyn,davkean/roslyn,KirillOsenkov/roslyn,MichalStrehovsky/roslyn,diryboy/roslyn,physhi/roslyn,ErikSchierboom/roslyn,MichalStrehovsky/roslyn,VSadov/roslyn,AdamSpeight2008/roslyn-AdamSpeight2008,genlu/roslyn,sharwell/roslyn,tannergooding/roslyn,jasonmalinowski/roslyn,eriawan/roslyn,bartdesmet/roslyn,AmadeusW/roslyn,wvdd007/roslyn,KirillOsenkov/roslyn,bartdesmet/roslyn,aelij/roslyn,AdamSpeight2008/roslyn-AdamSpeight2008,swaroop-sridhar/roslyn,dpoeschl/roslyn,ErikSchierboom/roslyn,mavasani/roslyn,jasonmalinowski/roslyn,stephentoub/roslyn,dotnet/roslyn,xasx/roslyn,nguerrera/roslyn,mgoertz-msft/roslyn,mavasani/roslyn,physhi/roslyn,jmarolf/roslyn,shyamnamboodiripad/roslyn,weltkante/roslyn,tannergooding/roslyn,abock/roslyn,jmarolf/roslyn,panopticoncentral/roslyn,sharwell/roslyn,tmat/roslyn,genlu/roslyn,nguerrera/roslyn,mgoertz-msft/roslyn,AdamSpeight2008/roslyn-AdamSpeight2008,DustinCampbell/roslyn,gafter/roslyn,abock/roslyn,AlekseyTs/roslyn,jcouv/roslyn,wvdd007/roslyn,heejaechang/roslyn,stephentoub/roslyn,reaction1989/roslyn,gafter/roslyn,shyamnamboodiripad/roslyn,cston/roslyn,mgoertz-msft/roslyn,AlekseyTs/roslyn,KevinRansom/roslyn,stephentoub/roslyn,dotnet/roslyn,genlu/roslyn,jcouv/roslyn,dpoeschl/roslyn,swaroop-sridhar/roslyn,dotnet/roslyn,reaction1989/roslyn,CyrusNajmabadi/roslyn,tannergooding/roslyn,VSadov/roslyn,AlekseyTs/roslyn,shyamnamboodiripad/roslyn,heejaechang/roslyn,xasx/roslyn,brettfo/roslyn,abock/roslyn,ErikSchierboom/roslyn,weltkante/roslyn,agocke/roslyn,agocke/roslyn,AmadeusW/roslyn,AmadeusW/roslyn,tmat/roslyn,reaction1989/roslyn,physhi/roslyn,davkean/roslyn,xasx/roslyn,davkean/roslyn,aelij/roslyn,bartdesmet/roslyn,KevinRansom/roslyn,wvdd007/roslyn,aelij/roslyn,eriawan/roslyn,brettfo/roslyn,brettfo/roslyn,CyrusNajmabadi/roslyn,heejaechang/roslyn,sharwell/roslyn,jcouv/roslyn,jmarolf/roslyn,diryboy/roslyn