View source for Update the quota usage when instances are shutdown

<big><big><big><big>Update the quota usage when instances are shutdown</big></big></big></big>

== Summary ==
Today when the instances are shutdown, the user cannot reuse the resources on the hypervisor since the quota still use the resources, which restricts from reusing the resources.
== Release Date ==
Post Havana 
== Rationale ==
More the flexibility given to user, the better it would be for adoption of Openstack Nova. If we could provide user with the reuse of resources of shutdown instances by providing resource calculation at instance startup & shutdwon it would definitely improve the user experience.
== User Stories ==
As a Openstack End User I want to reuse the resources such as RAM,VCPUs when the instaneces are shutdown
== Design ==
TBD
== Implementation ==
=== Code Changes ===
TBD
== Test Plan ==
TBD
== Demo Plan ==
TBD