Object Store: Set default wsgi workers to cpu_count

Patch Ifa563d22952c902ab8cbe1d339ba385413c54e95 introduces the option
"auto" for workers and also changes max_clients location in the sample files.

The documentation for workers was updated and for max_clients added.

Change-Id: Ia64385d791ba8677c3c356ecb49d50b6d27a3533
Closes-Bug: #1200484