core : Introduce engine_sessions table and DAO

Introduce engine sessions table to hold the session
information for authenticated users and the dao to
manipulate the table

Change-Id: I4b4d9cfc3edc6084fc0436ecfd09c82d5ae57f5e
Bug-Url: https://bugzilla.redhat.com/1092744
Signed-off-by: Ravi Nori <rnori@redhat.com>