Moved identical error message constructors to a function
Added jwt.py to authentication
Merge branch 'master' of https://github.com/iPlantCollaborativeOpenSource/atmosphere
Created AccountProvider, Core removed from service

Removed core code from service/accounts/*.py and centralized the logic in
core.Group, Identity and Quota.

Next task: Removing settings.OPENSTACK_* and settings.EUCA_* from the project in place of
the new providercredentials. This will allow us to pave the way for multi-provider support.
	new file:   core/migrations/0015_auto__add_providercredential__add_provideradmin.py
	new file:   core/migrations/0016_build_provider_admin_and_creds.py
	new file:   core/migrations/0017_auto__del_provideradmin__add_accountprovider.py
	modified:   core/models/__init__.py
	modified:   core/models/credential.py
	modified:   core/models/group.py
	modified:   core/models/identity.py
	modified:   core/models/provider.py
	modified:   core/models/quota.py
	modified:   scripts/add_openstack_user.py
	modified:   scripts/import_core_services.py
	modified:   scripts/import_users_from_openstack.py
	modified:   service/accounts/eucalyptus.py
	modified:   service/accounts/openstack.py
API back up after name change on identity function