Clean up local variable usage - Backends

Combines cleanup for mysql, postgresql and rpc

Change-Id: I37b928a669146671c946fc1ccb8e3ef1a27a3891
Fixes tempest script to accomodate Storage Vendor Names with spaces.

Change-Id: Ic651fbffaba9a9723ab572e8e8b732f6bea6d1c6
Closes-Bug: 1329597
Merge "Fixes tempest script to accomodate Storage Vendor Names with spaces."
Merge "Clean up local variable usage - Backends"