refactor/unify driver version strings

refactor/unify driver version strings

This patch updates each driver to provide
the same mechanism for reporting the version
of the driver.  It also includes fixing the
reported driver version at get_volume_stats()
time to be the version set in the driver.

When the manager starts the driver it now
logs the driver's name and version in the log file.

fixes Bug #1212878

Change-Id: Icefd065f885ad417735490e6ac90e2b21557d2dc