set HOME env var, in addition to java prop user.home
set HOME env var, in addition to java prop user.home

Somehow sbt was not finding deps for the compile step.
Setting HOME didn't turn out to be the fix, but
seems like a good paranoia thing to do anyway,
so leaving this change in.

phdezann/heroku-buildpack-scala,yannickdeturck/heroku-buildpack-scala,phdezann/heroku-buildpack-scala,heroku/heroku-buildpack-scala,Javilete/buildpack,Javilete/buildpack,hpcloud/heroku-buildpack-scala,Sage-Bionetworks/heroku-buildpack-scala,alexandru/heroku-buildpack-intentbrite,Scalingo/scala-buildpack,hpcloud/heroku-buildpack-scala,Luze26/heroku-buildpack-scala,agideon/heroku-buildpack-scala,KimStebel/heroku-buildpack-scala,yannickdeturck/heroku-buildpack-scala,shunjikonishi/heroku-buildpack-scala-compiled,Sage-Bionetworks/heroku-buildpack-scala,skyshard/heroku-buildpack-scala,shunjikonishi/heroku-buildpack-scala-compiled,KimStebel/heroku-buildpack-scala,talenthouse-dev/heroku-buildpack-scala,tmnd1991/heroku-buildpack-scala,agideon/heroku-buildpack-scala,jasonklarsen/heroku-buildpack-scala,heroku/heroku-buildpack-scala,Scalingo/scala-buildpack,Luze26/heroku-buildpack-scala,typesafehub/heroku-buildpack-scala,ryanbrainard/heroku-testpack-scala,jamesward/heroku-buildpack-scala,cloudControl/buildpack-scala