Quotas by Volume Type

The VolumeTypeQuotaEngine creates a volume, snapshot, and gigabyte
quota for each volume type that exists, in addition to the existing
global quotas for each. These are queried every time a quota operation
happens.

Add a table for storing quota default values. These values are used
before values in the config file. This allows the user to add a volume
type, and add a default quota for it with no downtime.

The volume type quotas also can be defined in the config file under the
keys:
quota_volumes_<vtype>, quota_gigabytes_<vtype>, and
quota_snapshots_<vtype>.

Another patch will have changes to cinderclient for setting project
quotas by volume type.

blueprint quotas-limits-by-voltype
DocImpact

Change-Id: I88261676edcd6eb5b7cea40654a931f32c00815c