engine: allow to fetch all QoS for REST

Added All QoS Dao object & relaxed common and dal.

Change-Id: I1e55d3e7643c42f48c971400b15f6eb92e50ccaa
Bug-Url: https://bugzilla.redhat.com/1085049
Signed-off-by: Gilad Chaplik <gchaplik@redhat.com>