Add response schema validation for volume limits

This is to add response schema validation for volume limits.
Besides, totalSnapshotsUsed should be integer in the response
of "Show absolute limits for project", I48f61f50defe9782d5a7afb7d7fa245f562785a0
will fix the api doc.

Change-Id: I245dd944f29681f3f41febafa7901f8f233a2776
partially-implements: blueprint volume-response-schema-validation
2 files changed