Added failure message for 'is already defined as object'
Added failure message for 'is already defined as object'

heroku/heroku-buildpack-scala,yannickdeturck/heroku-buildpack-scala,Scalingo/scala-buildpack,agideon/heroku-buildpack-scala,agideon/heroku-buildpack-scala,Scalingo/scala-buildpack,heroku/heroku-buildpack-scala,yannickdeturck/heroku-buildpack-scala