Make GPFS driver compliant with logging standards

This patch adds the log level markers (_LI, _LE or _LW) where they
were missing.  It also changes the use of '%' to ',' for inserting
variables into log messages.  These changes are made based on the
guidelines in:
http://docs.openstack.org/developer/oslo.i18n/guidelines.html

Change-Id: I46dc4855776638a133a65451c7e32269dd09b8d1
Partial-Bug: 1384312
Merge "Make GPFS driver compliant with logging standards"