core: DB, DAO and related BE patch for external..

core: DB, DAO and related BE patch for external tasks support

Change-Id: I04a2d92fecd43d218f82e39c3a85f27cd3fad1e8
Signed-off-by: Eli Mesika <emesika@redhat.com>
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=872719