OMERO.fs tidy dev_4_4

Changes to the OMERO.fs file hadn't been rebased because they were specific to the develop branch, leaving dev_4_4 with an out-of-date page that was confused between OMERO.dropbox and planned FS changes. This makes the dev_4_4 version as close to the develop version as possible. 

Note - because the relative links to the docs and product pages are branch-specific, I can't link to OMERO 5 without putting a full external hard-coded link into this page, which I want to avoid.