Defaults for DATASOURCE_USER & DATASOURCE_PASSWORD to None

[oh2fih]

Fixes mongo url without user/password after #291.

Cause

The #291 adds this if statement:

if self.config.DATASOURCE_USER is None
and self.config.DATASOURCE_PASSWORD is None

This condition is never met, because those variables have default values and it is impossible to explicitly set them to None, as None from an environment variable is treated as a string instead of Python None Keyword.

Before

DATASOURCE_USER	DATASOURCE_PASSWORD	self._datasource_connection_details
(unset)	(unset)	{'host': 'mongodb://cvexplore:[email protected]:27017'}
None	None	{'host': 'mongodb://None:[email protected]:27017'}

After

DATASOURCE_USER	DATASOURCE_PASSWORD	self._datasource_connection_details
(unset)	(unset)	{'host': 'mongodb://127.0.0.1:27017'}
cvexplore	password	{'host': 'mongodb://cvexplore:[email protected]:27017'}

[P-T-I]

Great! Thanks!