Adding undercloud ceilometer

-making whole Undercloud UI and dependent elements optional
 but included by default
-adding Undercloud Ceilometer that will collect statistics
 about Overcloud nodes, via SNMP
-adding SNMPd elements to all overcloud nodes

Change-Id: I31a577e298a9d0253e9b735be962fc384edc7b22
Merge "Adding undercloud ceilometer"