Provide explicit help string of resource-metadata

Currently, the "--resource-metadata" in ceilometer sample-create command
is not easy to use. For compatibility, this patch just provides an
explicit help string for the parameter.

Change-Id: I6d68d5b653c3b33808cba6f9a781301fba9b44e3
Closes-Bug: #1324759
Fix the alarm history order shown to user

In the Ceilometer storage backends implementation we are specially
sorting the alarm history points in the following way:
the first one by the timestamp should be the last one in the list.
The Python client itself provides the information in this way, but
the table printed had the opposite one, so this was fixed.

Change-Id: If39bb5868e360f37ed76c12b55fc71eade331f47
Merge "Provide explicit help string of resource-metadata"
Updated from global requirements

Change-Id: Ic2fd2ffb3d5c464d51933e97c6715f8608770487