Set default wsgi workers to cpu_count

Change the default value of wsgi workers from 1 to auto.  The new default
value for workers in the proxy, container, account & object wsgi servers will
spawn as many workers per process as you have cpu cores.

This will not be ideal for some configurations, but it's much more likely to
produce a successful out of the box deployment.

Inspect the number of cpu_cores using python's multiprocessing when available.
Multiprocessing was added in python 2.6, but I know I've compiled python
without it before on accident.  The cpu_count method seems to be pretty system
agnostic, but it says it can raise NotImplementedError or sometimes return 0.

Add a new utility method 'config_auto_int_value' to pull an integer out of the
config which has a dynamic default.

 * drive by s/container/proxy/ in proxy-server.conf.5
 * fix misplaced max_clients in *-server.conf-sample
 * update doc/development_saio to force workers = 1

DocImpact

Change-Id: Ifa563d22952c902ab8cbe1d339ba385413c54e95
Merge "Set default wsgi workers to cpu_count"