3PAR: Backend assisted volume migrate

3PAR: Backend assisted volume migrate

This patch implements volume migrate using native 3PAR APIs.

Prerequisites:
1. Same 3PAR backend
2. Volume cannot be attached
3. Source and Dest CPGS are in the same domain

Steps:
1. Create a temporary volume in the destination with a copy of the source
2. Wait for the copy to complete
3. Delete the source
4. Rename the temporary to the same name as the original

Change-Id: Ia42503d41bf8afd908cd3ffb0288f0d353f313f1
Implements: blueprint native-3par-migrate-volume