Fixed erroneous force full copy in ceph backup driver

The following steps should not result in a forced full copy:

1. create vol
2. create backup (works fine i.e. uses incremental diff)
3. delete backup
4. create new backup (full copy forced because volume backup-snap exists and is not ignored)

This patch resolves the above problem.

Change-Id: I61c245219f54f7ee942e06e343c5d79d4cab947b
Fixes: bug #1221836
fix missing unit in log message

Bad log message:
    "extend volume 1 to 2"
Correct one:
    "extend volume 1 GB to 2 GB"

(also update my profile in .mailmap)

Change-Id: I6d229c4440f2f5443b45a10f3912c20e21c63f32
Move novaclient to requirements.txt

novaclient is a runtime requirement in Havana both for volume
migration and qemu-assisted-snapshots.

Closes-Bug: #1223484
Change-Id: Ie7e8be2d0edf00cdb04f980a6aa247e04807bf67
Merge "Fixed erroneous force full copy in ceph backup driver"
Merge "fix missing unit in log message"
Merge "Move novaclient to requirements.txt"