restapi: Adding support for copy/move disk from disk collection.

Adding support for the following urls:
/api/disks/{disk:id}/copy
/api/disks/{disk:id}/move

Change-Id: I516341d3e033a94a997ac5320312e75a5ed1576c
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=911348
Signed-off-by: Sergey Gotliv <sgotliv@redhat.com>