added test for priming ivy cache for play apps
added test for priming ivy cache for play apps

heroku/heroku-buildpack-scala,KimStebel/heroku-buildpack-scala,yannickdeturck/heroku-buildpack-scala,shunjikonishi/heroku-buildpack-scala-compiled,Scalingo/scala-buildpack,Scalingo/scala-buildpack,KimStebel/heroku-buildpack-scala,yannickdeturck/heroku-buildpack-scala,phdezann/heroku-buildpack-scala,Luze26/heroku-buildpack-scala,Javilete/buildpack,Luze26/heroku-buildpack-scala,agideon/heroku-buildpack-scala,Javilete/buildpack,hpcloud/heroku-buildpack-scala,agideon/heroku-buildpack-scala,Sage-Bionetworks/heroku-buildpack-scala,hpcloud/heroku-buildpack-scala,heroku/heroku-buildpack-scala,phdezann/heroku-buildpack-scala,shunjikonishi/heroku-buildpack-scala-compiled,Sage-Bionetworks/heroku-buildpack-scala