os-brick should use oslo_log for logging

[Tomoki Sekiyama]

Currently, the following code will fails by exception "oslo_config.cfg.DuplicateOptError: duplicate option: default_log_levels".
When "from os_brick.initiator import connector" is commented out, the exception doesn't occur.
This is because os-brick is not using oslo_log but using oslo-incubator's logging.py.
This should by replaced with oslo_log.

*Code to reproduce the bug:

 from os_brick.initiator import connector
 from oslo_log import log as logging
 from oslo_config import cfg

 CONF = cfg.CONF
 logging.register_options(CONF)

*Result:

 Traceback (most recent call last):
   File "test.py", line 6, in <module>
     logging.register_options(CONF)
   File "/usr/lib/python2.7/site-packages/oslo_log/log.py", line 202, in register_options
     conf.register_opts(_options.log_opts)
   File "/usr/lib/python2.7/site-packages/oslo_config/cfg.py", line 1794, in __inner
     result = f(self, *args, **kwargs)
   File "/usr/lib/python2.7/site-packages/oslo_config/cfg.py", line 1951, in register_opts
     self.register_opt(opt, group, clear_cache=False)
   File "/usr/lib/python2.7/site-packages/oslo_config/cfg.py", line 1798, in __inner
     return f(self, *args, **kwargs)
   File "/usr/lib/python2.7/site-packages/oslo_config/cfg.py", line 1940, in register_opt
     if _is_opt_registered(self._opts, opt):
   File "/usr/lib/python2.7/site-packages/oslo_config/cfg.py", line 573, in _is_opt_registered
     raise DuplicateOptError(opt.name)
 oslo_config.cfg.DuplicateOptError: duplicate option: default_log_levels

[Tomoki Sekiyama (tsekiyama)]

A patch to fix this bug is proposed:
  https://review.openstack.org/#/c/173106/

[Vilobh Meshram (vilobhmm)]

Looks like tsekiyama alreadys tarted working on this. Came to know about this when I proposed the fix https://review.openstack.org/#/c/173500/ so I abandoned it. Moving it back to tsekiyama.

[Michal Dulko (michal-dulko-f)]

These bugs should be reported for os-brick as Launchpad project is already there. ;)

[Walt Boring (walter-boring)]

This bug has already been addressed in os-brick. You can check the latest code in

https://github.com/openstack/os-brick