Wrapped Imbo\Database\Doctrine::getStatus() in a try/catch.

This ensures that getStatus() will return false even if connect() throws a PDOException - which it will on incorrect credentials.
Added missing parenthesis
Updated ChangeLog
Renamed the travis profile to no-cc
Started working on a CONTRIBUTING file
Added a link to Sphinx docs
Added note about installing dev requirements
Merge pull request #314 from christeredvartsen/contributing

Added contribution guidelines
Added a note regarding pull requests. Also updated the commands regarding running tests in the docs
Documented RO/RW private keys + custom user lookup adapters