Release version fix

The changes in this PR:

- fix the `init-version` target in the case of a tag match (preventing the `DEV` appending)
- add support for lightweight tags
- displays the release version in the `init-version` target

To test this PR,
- check the outcome of the [BIOFORMATS-trunk-release](http://hudson.openmicroscopy.org.uk/job/BIOFORMATS-trunk-release) job
- locally tag and build Bio-Formats and check the `release.version` is correctly set, e.g.  `git tag vx.y.z && ant clean tools`