Adding GPFS Manila driver

Supporing GPFS exports over kernel NFS and Ganesha NFS
Supporting following Manila functionality:
1. Create, List, Delete Shares
2. Create, List, Delete Share Snapshots
3. Create Share from a Share Snapshot
4. Allow, Deny access to a share based on IP

Supports, local and remote GPFS nodes to the Manila service node,
in a GPFS cluster

Limitation:
1. While using remote GPFS node, with Ganesha NFS, 'gpfs_private_key'
for remote login to the GPFS node must be specified and there must be
a passwordless authentication already setup between the Manila and the
remote GPFS node.

DocImpact

Implements: blueprint gpfs-driver
Change-Id: I6664054ba52d03814cea846cb0d79cd853632814
Merge "Adding GPFS Manila driver"