Provision browser tests for CentralAuth
Provision browser tests for CentralAuth

Configures additional environment variables used by browser tests and
converts the selenium user to use a global account.

Change-Id: If2aefdabc513de332901d09bf7b2c2699a8932ba

stuartbman/mediawiki-vagrant,HarriAlasi/wiki3dviewer,ankita-kumari/mediawiki-vagrant,wikimedia/mediawiki-vagrant,HarriAlasi/wiki3dviewer,wikimedia/mediawiki-vagrant,stuartbman/mediawiki-vagrant,ankita-kumari/mediawiki-vagrant,wikimedia/mediawiki-vagrant,stuartbman/mediawiki-vagrant,ankita-kumari/mediawiki-vagrant,stuartbman/mediawiki-vagrant,HarriAlasi/wiki3dviewer,ankita-kumari/mediawiki-vagrant,HarriAlasi/wiki3dviewer,ankita-kumari/mediawiki-vagrant,wikimedia/mediawiki-vagrant,HarriAlasi/wiki3dviewer,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,stuartbman/mediawiki-vagrant,stuartbman/mediawiki-vagrant,HarriAlasi/wiki3dviewer,HarriAlasi/wiki3dviewer,ankita-kumari/mediawiki-vagrant,stuartbman/mediawiki-vagrant