Add an extra property for selecting SCG / Storage Template

In order to select an SCG / Storage Template , we add an extra
 propertity to image properties , UI could use this data to format
the data for user to select the specific SCG / Storage Template ,
and also, other components which consumes PowerVC images in
Openstack can also leverage this.

Change-Id: I4b9dba719dada3823dc159748d15a3266ca9efa3
Closes-Bug: #1362904
Merge "Add an extra property for selecting SCG / Storage Template"