ModifyVolume attributes on Clone.

Clones copy over the attributes from the source volume,
we want to keep some admin data like source-volid and if
it's a clone or not.  To do that we just need to call modifyvolume
after the clone operation and update this info.

Change-Id: I903fe6f8a57880abad8d315d091c1e57624a519c
Merge "ModifyVolume attributes on Clone."