Add `--match v.[0-9]*` to `git describe`

In order to prevent non-official tags from causing
server/client version breakage, filter out all non
official-looking tags, i.e. "v.4.4.9"

see: http://trac.openmicroscopy.org.uk/ome/ticket/11727

#### Testing ####
 * All jobs should remain green and version numbers should still look reasonable.
 * Adding a fake ticket (`git tag -a foo_bar`) should **NOT** affect the output of `./build.py version`