ome-io/plugins removal

Removes the ome-io component completely, partially by deleting OME-Perl support and by moving some classes to OMERO (See openmicroscopy/openmicroscopy#2103).

ome_plugins is also completely removed, and ome-tools is left with little reason for existence.

Some minor comments/descriptions in the build system were also modified to simplify grepping. If these should be stripped out, let me know. As of https://github.com/joshmoore/openmicroscopy/commit/153b54d91bcb18ce96c4012e9b7d75ee54529f1b, these changes compile with ant, mvn, and build.py, the server launches as do both the BF and the Insight plugins.

One large question is whether or not the renaming of `common` to `format-common` was necessary. I'm happy to roll that back, but it will require more OMERO changes.