core: SnapshotDao - added getAllByStorageDomain method

SnapshotDao/DbFacadeImpl:
* Added getAllByStorageDomain method.

snapshot_sp.sql:
* Added GetAllSnapshotsByStorageDomainId stored procedure.

Change-Id: I13a5d3493be9f26caa0d6f4e15a9c6c9d308cfd9
Signed-off-by: Daniel Erez <derez@redhat.com>