Add a Bitdeli badge to README
Merge pull request #37 from bitdeli-chef/master

Add a Bitdeli Badge to README
Update .travis.yml
Update README.rst
Update contribute.rst
Merge branch 'develop' of github.com:ITCase/sqlalchemy_mptt into path-33
Merge branch 'master' of github.com:ITCase/sqlalchemy_mptt into path-33
Flushing the session now expire the instance and it's children fixes #33