Changes Volume Prefix From mysql To datastore

changes the volume name from mysql-<uuid> to datastore-<uuid>. now
that multiple datastore types are supported, the volume name prefix
should not be hardcoded to "mysql-" so as to avoid confusion to the
user and/or cloud administrator.

Change-Id: Ib585eab42f609095dee709b6e6e5eb980eff42af
Closes-Bug: #1277401
Fix internal error generated from config-detach

Log debug statement referred to an attribute that could be null
Moved the statement to below the check for null

Change-Id: Ib69584e5eb1723734cb8b8af2761d29a79034942
Closes-Bug: #1302657
Merge "Fix internal error generated from config-detach"
Merge "Changes Volume Prefix From mysql To datastore"