Standardize logging in volume.api.py

Standardize logging in volume.api.py

We now have resource tag support in oslo logging,
and our logging is pretty inconsistent and down right
ugly in places.  Let's clean things up based on the
standard logging guidelines and use the fancy new
resource tag.

This patch starts with the volume.api file as that's
'easy', so we can enforce things going forward and start
working out other files in future patches.

To use set the following in cinder.conf:
logging_context_format_string = \
%(asctime)s.%(msecs)03d %(levelname)s %(name)s [%(request_id)s \
%(project_name)s] %(resource)s%(message)s

Change-Id: I78708ba8bc372c2ca051aa7d84386dc7125a9b5e