Core/tasks/machine.py doesn't work, moved the task to service/tasks/driver.py
ATMO-328 Fix delta in API endpoints with allocations.

* Add service.allocation.get_delta method.
* Move profile and IdentityMembership to use get_delta method.
* PEP8 Compliance.

	modified:   core/models/group.py
	modified:   core/models/profile.py
	modified:   service/allocation.py
	modified:   service/instance.py
Merge branch 'atmo-328'