Document latest changes to the Homebrew OMERO formula

- Ice (3.5) is now the default version installed by `brew install omero`
- Add options to use old 3.3 and 3.4 versions
- Update PYTHONPATH setting in the configuration section
Add note about SLICEPATH for development server
Add note about .bash_profile
Updating Demo server availability for 5.0.x
Fixing webclient & webstart links I missed
Server address update
Merge pull request #638 from sbesson/rebased/dev_5_0/homebrew_4410

Document latest changes to the Homebrew OMERO formula (rebased onto dev_5_0)
Add --devel option to install the OMERO 5 via Homebrew
Updating screenshots
Listing demo before VA again
Merge pull request #644 from sbesson/omero5_homebrew_devel

Add --devel option to install the OMERO 5 via Homebrew
Adding demo server to main index new list
Merge pull request #642 from hflynn/demo-server-5

Updating Demo server availability for 5.0.x