fix rake detection when DATABASE_URL not present

Introduced `rake_env` to LanguagePack interface. Renamed `default_database_url` to `database_url`.
travis
Merge pull request #214 from heroku/schneems/database_url_issue

fix rake detection when DATABASE_URL not present
update changelog
push to github before tagging/releasing
bump to v101
fix github_remote extraction
pass output options to pipe
actually use the blacklist env vars
Merge pull request #225 from heroku/path_debug

more pony fixes
update changelog
bump to v102
restrict Rails 4 detect to be 4.0.x only
set config vars on first push again
Rails 4.1 support

* don't write `config/database.yml` in Rails 4.1, See https://github.com/rails/rails/pull/13463#issuecomment-31480799.
* setup env var SECRET_KEY_BASE for Rails 4.1's `config/secrets.yml`
Merge pull request #227 from heroku/rails41

Rails 4.1.0 Support
update changelog
bump to v103
rev hatchet version
Merge pull request #228 from heroku/schneems/rev-hatchet

rev hatchet version