Correct models and add test for overlapping shifts
Merge remote-tracking branch 'spacedman/master'
Add mutex to ShiftType to allow overlap of annual leave
Add test validation for day not following night and visa versa
Update fixtures
Fix some model validation bugs
Move installing repo dependancies till after pulling repo
Correctly set debug value
Set ALLOWED_HOSTS in settings
Correct outcome fixtures and allow ShiftType.time_of_day to be blank
Add HOST to dev.env