first pass at quota state management

Change-Id: Ie4f6d71f463e128ebb532766ffb5dad37bbebecd
Flesh out API some more.

Merge branch 'master' of github.com:epim/nova-specs

Conflicts:
	specs/juno/quota-state-management.rst

Change-Id: I37976eca911016ae90b23668f3d1b7c0bca04945