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
Remove references to FLAGS from volume/manager.py

Note that we still must import flags.py because volume_topic is defined
in the list global_opts in flags.py.

Fixes bug #1153551

Change-Id: I3d37bde4ba895c110390cea92385344ff94cb7d1
Remove AGPL rtslib pkg from pip-requires.

Fixes bug: 1157091

Change-Id: I1879712ab33324740496b284500fa2b22a1bc310
CoraidDriver: retrive volume info (improvement)

Some portions of code into this method are useless since
the REST API on Coraid side has been improved.

Fixes bug #1157242

Change-Id: Ie37b5b76710e77acb2acf627c9688e4f931e686c
Merge "CoraidDriver: retrive volume info (improvement)"
Merge "Remove references to FLAGS from volume/manager.py"
Merge "Pull Oslo log fix to enable root logger initialization"