added support for release candidate versions of sbt
Improved sbt version regex to accept more types of versions. improved tests
added a publish script
increase thread stack size to 4M during compilation to avoid StackOverflow errors
Merge branch 'master' of https://github.com/heroku/heroku-buildpack-scala

Conflicts:
	bin/compile
Merge branch 'master' of github.com:gloopeezza/heroku-buildpack-scala