_fs_deletelog via triggers

This PR bumps the DB patch to 3 and adds the
new table _fs_deletelog (not in Hibernate) as
wel as triggers to fill it. omero.cmd.Delete
on OriginalFile objects now properly removes
them from the repository. The linkages between
images and originalfiles are not yet handled.

Testing from the UIs may be difficult since
there is no direct access to files in FS, nor
are there any links between images and those
files to trigger the removal. That will be a
next PR.

NB: This is currently based on raw-file-access.
Once that is merged I can rebase.