This fixes the following error when running the tests:
E ModuleNotFoundError: No module named 'pytz'
Instead of pytz only pytz-deprecation-shim was installed.
TODO Check if "pytz" can be removed from requirements.txt later on.
* Add environment variables for Database configuration.
* Install postgres and mysql dependencies.
* Test refactoring
* Run tests for prosody with postgres and also for prosody with sqlite.
* Add tests that check if postgres or sqlite is used.
Created a tests folder which contains pytest and bats tests.
Pytest is used to login and send messages to other accounts.
Bats is used to check the log for debug messages.
This fixes#13.
