Drop --use-mirrors from .travis.yml
Merge pull request #649 from sbesson/rebased/develop/travis_pypi

Drop --use-mirrors from .travis.yml (rebased onto develop)
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 645 (Add --devel option to install the OMERO 5 via Homebrew (rebased onto develop))