Made Ambari RPM location configurable

The Ambari RPM location is now an ambari configuration property in
the blueprint.  This will support debug/issue resolution scenarios
as well as the export of this information.

Fixes:  bug #1208966

Change-Id: Ie0bfbd39d687c8c26d654b7fcfb369f764d48ef2
(cherry picked from commit f9a7b209083734a37ca8a6c844c785bf95c46772)