Tests refactor

This is a set of things that should be done to improve testing:

• Make use of the (overriding settings)[https://docs.djangoproject.com/en/1.7/topics/testing/tools/#overriding-settings] capabilities of django rather than have separated settings file
• Rewrite tests so that common code/behavior is tested in one place and only module specific tests are written in submodule
• Add tests that follow all possible code path (e.g. forking, creating a new version)
• Add tests for variable fields query
• Add website automated tests like suggested in #69