Added factory_boy package to project dependencies
Deleted non-used old fixture for user
Added autoflush mode to DB (it's the default behaviour in SQLAlchemy, but not in flask-SQLAlchemy, see https://github.com/rbarrois/factory_boy/issues/81)
Added model factories with factory_boy
Minor addition to user factory
Revert autoflush changes
Added custom create method for factories
First tests successfuly modified
Renamed test api base class
Modified api_common tests to use only factories + improvements in factories
App api tests with factories
Removed unnecessary stuff
Category api tests with factories
Fix: stats functions return 0 instead of None if the number_of_something is 0
Use factories in task api tests
Fixed bad class name in token api tests
Use factories in taskrun api tests
Created AnonymousTaskRun factory
Refactor in api tests
Use factories in token api tests + refactor