Version 5 0 4 release

This is the update to bring the github version into line with the active 5.0.4 version release.

To review check Home page, Getting Started Version 5, Importing Version 5, Resources and Previous pages. Make sure all 5.0.3 references have been updated to 5.0.4.

Will be viewable at: http://snoopycrimecop.github.io/ome-help/ 
I would precise `a pull request should be opened against the master branch of https://github.com/openmicroscopy/ome-help`