Update the OMERO install script to test Web login with CSRF

This commit patches OMERO-homebrew-install.sh to retrieve the CSRF token and
then pass it to the POST data in a second call testing the login.

To test this PR, check the http://ci.openmicroscopy.org/job/OME-5.0-merge-homebrew/ passes while testing the development Web server.

/cc @aleksandra-tarkowska