Code review comment for lp:~sandy-walsh/nova/zones3

From nova/flags.py:

flags.DEFINE_list('default_log_levels',
                  ['amqplib=WARN',
                   'sqlalchemy=WARN',
                   'boto=WARN',
                   'eventlet.wsgi.server=WARN'],
                  'list of logger=LEVEL pairs')

I think that is a good pattern to follow. Your argument ends up looking like

--zone_capabilities=hypervisor=xenserver,os=linux

You'll end up with the list

['hypervisor=xenserver', 'os=linux']

You're definitely treating it as a list by splitting and iterating over it, so DEFINE_list seems reasonable. Based on your comments it looks like you might specify multiple values for any individual capability, in which case using a comma would break the flag list, maybe using a colon as the item separator would be reasonable?