Fixed Python runtime according to the official Heroku doc

See https://devcenter.heroku.com/articles/python-runtimes#supported-runtimes
Update Heroku Postgresql default add-on to hobby-dev
Merge pull request #114 from catsby/update_default_postgresql

Update Heroku Postgresql default add-on to hobby-dev
Merge pull request #113 from zyegfryed/patch-3

Fixed Python runtime according to the official Heroku doc
third argument support for envs in compile
chmod +x
chmod +x
fix sub-env for when env file is not present
sticky runtimes
sticky python versions bugfix
new buildpack env standard
update runtime docs, thanks @uniphil!

#117
fix url to testing buildpack
Merge pull request #118 from uniphil/master

fix url to testing buildpack
Update to Setuptools 2.1 and Pip 1.5.2

So seamless.
Merge remote-tracking branch 'origin/master'
--allow-all-external
pip v1.5.4