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
Update link to logback-cli.xml
Updating Demo server availability for 5.0.x
Fixing webclient & webstart links I missed
Server address update
merge dev_5_0 -D org -I include -E exclude: PR 638 (Document latest changes to the Homebrew OMERO formula (rebased onto dev_5_0))
merge dev_5_0 -D org -I include -E exclude: PR 640 (Update docs for import and logging fixes)
merge dev_5_0 -D org -I include -E exclude: PR 642 (Updating Demo server availability for 5.0.x)