Add Availability Zone to Volume screens

User should be able to choose an AZ (or make unspecified) when creating a volume
AZ should be visible in Volumes table
AZ list should come from Cinder

Change-Id: I23314dedc3eb65454df32102b0a96174f8030d81
Closes-Bug: #1230288
(cherry picked from commit 00f8b11d956cbdee1bbe06a67b79127b6e3e330f)
Make volume AZ selection compulsory

Change-Id: I74c961bb3d8b6e9d4a074ce69dcf2e832741c14f
Get volume AZ list from settings for Grizzly Cinder

Change-Id: Ia33e5d8e0cfc451bfd6c9aef58d105cd69e5fec1