Use `git describe` for Bio-Formats version (See #9639)

Current releases 2 PRs in the BF repository: 1 to bump the version numbers to the release value (`4.5-DEV` --> `5.0.0-beta1`) and one to bump to either rollback or to bump to new DEV versions (`5.0.0-beta1` --> `4.5-DEV` or `5.0.0-beta2-DEV`)

Tasks/features involved:
 * [x] Add git describe commands and regexes to `ant/common.xml`
 * [x] Remove hard-coded references to the version from `build.properties` files and source
 * [x] Allow overriding by `omero.version`
 * [ ] Set version in maven (using perhaps [mavanagaiata](http://koraktor.de/mavanagaiata/usage.html) or [jgit-buildnumber](https://github.com/alx3apps/jgit-buildnumber)
 * [ ] Fix cppwrap header references (using string replacement?)