Install foreman
Update builder

Don't use foreman if no Procfile was found
Merge branch 'master' into foreman

* master:
  overwrite source.list
  change repo before prepare task
  Fix for deprecated repository
Merge branch 'master' into foreman
Merge branch 'master' into foreman
Merge branch 'master' into foreman
Revert back to Ubuntu 12.04, because 14.04 breaks buildstep
Reorganize buildpacks, because order matters
Merge remote-tracking branch 'origin/master' into foreman
Merge branch 'master' into foreman

* master:
  Use offical PHP buildpack
Added erlang support
Updated README and AUTHORS
Added build step tests

- Added erlang build pack
- Added Wercker-CI support