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
Merge "refactor/unify driver version strings"