Quota feature

Quota check for create/delete/resize volume
Quota is implemented as a decorator, which can be easy enabled and disabled if wanted.
The quota feature uses a reservation system that reserves resources prior to usage.

BP https://blueprints.launchpad.net/reddwarf/+spec/quotas

Change-Id: I5df82c8f1d7b40311b5d5d7301992607f98e9b2a
Merge "Quota feature"