Changed api_key handling so it is used for token authentication
Fixed trailing ':' on Authorization header
Preload API key authentication
Fixed 401 error as described by pySilver

Empty api_key would result in validation error
relevant post:
https://github.com/marcgibbons/django-rest-swagger/pull/51#issuecomment-35352122
Merge branch 'master' of https://github.com/WhiteDawn/django-rest-swagger into develop
Removed Unipath dependency (Fixes #59)