Pull Oslo log fix to enable root logger initialization

Pull Oslo log fix to enable root logger initialization

Previous log module in Oslo doesn't initialize root logger, which results
in lacking of log message for non-openstack library (such as stevedore).
This patch pull latest log module from Oslo, which has recently merged a
change to enable root logger initialization.

Notice that this change also includes one log modules fix in Oslo which
'unignore' log_format setting.  As a result, one may experience log format
change when using devstack.  To get old log format back, simply assign
a NULL string (aka nothing) to 'log_format' configure option in cinder.conf.
For example, just append cinder.conf with one new line 'log_format = '.

Fix bug: # 1131322

Change-Id: I86396f15ca152512ce6d18d6d424a855b27f495e