Beef up storage comments
Beef up storage comments

Add a few comment adjustments and changes to
the storage layer code comments.

Change-Id: I6e8ca80473d4db7588aeacb06d00e5d6774e4f7e

citrix-openstack-build/taskflow,citrix-openstack-build/taskflow,pombredanne/taskflow-1,junneyang/taskflow,openstack/taskflow,openstack/taskflow,varunarya10/taskflow,varunarya10/taskflow,pombredanne/taskflow-1,jimbobhickville/taskflow,junneyang/taskflow,jimbobhickville/taskflow