Fix "Download from OMERO" plugin for 4.4.x

See https://trac.openmicroscopy.org.uk/ome/ticket/10770

The ```omero_client.jar``` has been updated to ```4.4.8p1```, so the plugin should work again.  However, there is also a message at the top of the login dialog that suggests using the official OMERO ImageJ plugin instead, as the ```Download from OMERO``` plugin is not well supported.  We can later decide whether or not we want to remove it entirely in 5.x.x.