Reestructuring permissions, now discarted django-guardian, and using custom permission system
Reordering permissions on models
Defining more rest framework permissions handlers
Adding basic permissions management to documents and questions
Adding basic permissions management to wiki page
Removing django-guardian from installed apps
Now working correctly the create and modify user on the admin
Removing base/services.py now not needed
Merge branch 'master' into permissions
Merge branch 'master' into permissions

Conflicts:
	greenmine/scrum/api.py
	greenmine/scrum/models.py
Removing duplicated issues url on api_root