Release version fix

This PR fixes the `init-version` target in the case of a tag match (preventing the `-DEV` suffix appending)

To test:
- in Hudson. check the artifacts of the [BIOFORMATS-trunk-release](http://hudson.openmicroscopy.org.uk/job/BIOFORMATS-trunk-release) job
- locally tag and build Bio-Formats, e.g.  `git tag vx.y.z -m "Release x.y.z" && ant clean tools` then check `loci.format.FormatsTools.VERSION` does not have any `-DEV` suffix