Fix missing translations for log messages

Fix missing translations for log messages

Fixed log translations in volume.drivers and volume.manager modules
for error, info and warning messages with appropriate marker function
according to the logging standards [1].

As LOG.warn has deprecated [2] so I have changed LOG.warn to
LOG.warning.

[1] http://docs.openstack.org/developer/oslo.i18n/guidelines.html
[2] http://bugs.python.org/issue13235

Note: Any new occurrences added in master during the review can be
handled separately if they are not caught by hacking checks.

Partial-Bug: 1431256
Change-Id: I9b7b89097b296ea62b43f1d948dcf59e2e5a40c4