Make "quantum help" to show a list of subcommands.

Fix bug 1023260

All other OpenStack clients (nova, keystone, glance, ....) accepts
just "help" which displays a list of subcommands. This commit makes
quantum command consist with other OpenStack projects.

After this change help behavior of quantum command becomes as follows:
Show general help message:
  quantum --help
  quantum help
Show help message of subcommand
  quantum help <subcommand>
  quantum <subcommand> --help

Change-Id: I34ca0df809da04f9b9b9275c697e6aafca312cfe
Display subnet cidr information in net-list

Fixes bug 1074415

This commit introduces extend_list() in ListCommand class. This method
can be used to update a retrieved list (e.g., add additional information
or convert some field to more human-readable value).

Change-Id: Icf5ab616ab4d9add16c921e1944ba37b376b2ab2
Allow known options defined after position arguments.

We run the argument parser to split known options and unknown options.
Make '-' work and have the same effect as '_' in both known and unknown
option parts.
Make metavar Uppercase.

blueprint options-location

Change-Id: Ic27b278484133c8b83e3b031a0810a76b050219f
Merge "Display subnet cidr information in net-list"
Migrate from unittest to testtools

Part of blueprint grizzly-testtools

Change-Id: If92ba40209cb45905220df8c72501f33cdc4e1fc
Merge "Make "quantum help" to show a list of subcommands."