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
merge develop -D org -I include -E exclude: PR 626 (Add new Squash tutorial and screenshots)
merge develop -D org -I include -E exclude: PR 639 (Document latest changes to the Homebrew OMERO formula (rebased onto develop))