Add support for --timing options. Use cliff via a pseudo-command
'Timing' to support multiple outputformats.
If an output format other than the default 'table' is selected
use CSV since the timing data is in list form.
Will pick up timing data for any client object that has a method
similar to novaclient's get_timings().
TODO:
* Stop instantiating all of the clientmanager client objects just
to check for timing data. Descriptor magic required?
Change-Id: I7f1076b7a250fba6a8b24b2ae9353a7f51b792b2
4844a25779