core: Adds entity DwhHistoryTimekeeping and variable heartBeat

Adds store procedures to access dwh_history_timekeeping table.
Adds business entity DwhShistoryTimekeeping and its DAO.
Adds new variable 'heartBeat' to dwh_history_timekeeping table

Change-Id: Ib34301ea921b2fda9fb0e09927b0417c0c096aca
Bug-Url: https://bugzilla.redhat.com/962177
Signed-off-by: Martin Perina <mperina@redhat.com>