Merge remote-tracking branch 'heroku/master'

* heroku/master: (235 commits)
  bump to v102
  update changelog
  actually use the blacklist env vars
  pass output options to pipe
  fix github_remote extraction
  bump to v101
  push to github before tagging/releasing
  update changelog
  travis
  fix rake detection when DATABASE_URL not present
  remove run_with_env
  quote env vars
  read user ENV settings for both user-env-compile or buildpack-env-arg
  bump to v100
  take into account buildpack v99 was a noop
  update changelog
  bump to v99
  update changelog
  recompile psych if it's compiled with 0.1.4
  hatchet now takes care of `git config`
  ...

Conflicts:
	lib/language_pack/rails3.rb
Fix gem presence testing.

Incorporates the changes in c1bac44b.
Merge branch 'master' of github.com:ClearFit/heroku-buildpack-turbo-sprockets

# By Austin Ziegler
# Via Austin Ziegler
* 'master' of github.com:ClearFit/heroku-buildpack-turbo-sprockets:
  Fix gem presence testing.