Suspend script written by Darren Boss (@netscruff).
	new file:   scripts/suspend_instance.py
Added script for suspending instances
Merge branch 'herja' of github.com:iPlantCollaborativeOpenSource/atmosphere into herja
PEP8 Compliance.
	modified:   service/instance.py
BUGFIX - ATMO-431
Merge branch 'herja' of https://github.com/iPlantCollaborativeOpenSource/atmosphere into herja
Add --resume option.
	modified:   scripts/suspend_instance.py
Add support for request tracker
Merge branch 'abyssinian-nightjar' of github.com:iPlantCollaborativeOpenSource/atmosphere into abyssinian-nightjar
PEP8 Compliance.
	modified:   core/models/application.py
MachineRequest error fixed
Use django transactions and select_for_update to prevent race condition in instance_status_history.
	modified:   core/models/instance.py
Use django transactions and select_for_update to prevent race condition in instance_status_history.
	modified:   core/models/instance.py
Add suspend_instance from abyssinian-nightjar.
	modified:   scripts/suspend_instance.py
PEP8 Compliance. Add 'Enforcing' variable to settings, so that production can be tested
Merge branch 'herja' of https://github.com/iPlantCollaborativeOpenSource/atmosphere into herja
Catch system exit exceptions
Updated automated imaging tasks so that they run to completion, can be re-started at any point in time by running start_machine_imaging()
Merge herja+Abyssinian
Merge branch 'abyssinian-nightjar'