Change buildpack order
Merge pull request #96 from pahaz/master

Change buildpack order.
Hardcode stack name

The newer heroku buildpackes (for example ruby/rails) use the STACK
variable for caching and cache busting (due to the cedar-14 stack).
Without a STACK envvar the caching system is broken and results in the
whole set of gems being reinstalled
Merge remote-tracking branch 'origin/topic/stack_name'

Conflicts:
	stack/buildpacks.txt