Most Recent Observations should show up in dashboard header - TRUNK-439

TRUNK-439: Add Global property for dashboard header concepts and remove obsolete cd4_count concept.
Includes Migration.

By @wginolas and @jthoenes

Remove invisible patientHeaderObsReturnVisit from patientHeader.jsp.

@jthoenes, @wginolas

Add class to td element and adapt release test.

@wginolas and @jthoenes