Resolve AssumeNG from Bio-Formats jar repository

This PR supersedes https://github.com/openmicroscopy/openmicroscopy/pull/642 and removes the need for two versions of assumeng.jar being present in the project.

To test, import the top level ome.git project into Eclipse and make sure that bioformats/components/test-suite doesn't report any errors regarding missing classes.

After merging, @mtbc could use AssumeNG in his unit tests.