Add Mock to test requirements in setup.py
Add Mock to test requirements in setup.py

Ticket: #585
Branch: feature/585-track-contract-hour-extensions

arbitrahj/django-timepiece,gaga3966/django-timepiece,caktus/django-timepiece,arbitrahj/django-timepiece,caktus/django-timepiece,BocuStudio/django-timepiece,josesanch/django-timepiece,caktus/django-timepiece,gaga3966/django-timepiece,josesanch/django-timepiece,BocuStudio/django-timepiece,josesanch/django-timepiece,dannybrowne86/django-timepiece,gaga3966/django-timepiece,arbitrahj/django-timepiece,BocuStudio/django-timepiece,dannybrowne86/django-timepiece,dannybrowne86/django-timepiece