Merge pull request #48 from elemoine/docs

Docs improvements
Tip for mac users when installing psycopg2.
Merge pull request #49 from elemoine/tests

Get prepared for functional testing
Minor fixes to README.md
Add tearDown to TestProjectFunctional

The tearDown function calls DBSession.remove to dipose of the current session. This makes it possible to call DBSession.configure again in a next test.
Activate test_project__not_found again