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
Added a method for fetching image properties from the database
Started working on the event listener that will generate and choose image variations
Added some docs for the event listener
Event listener is up and running
Trigger a separate event that the Imagick event listener subscribes to
Added database and storage adapters for the image variations event listener
Support alternate ways of specifying the database and storage adapters
Updated tests
Added some integration tests for the storge and database adapters for the image variations event listener
Added support for specifying an image as an argument to the event