Tweak browsertests URLs

We need browsertests to mimic MediaWiki paths in production. Ie
something like:

 http://localhost:9413/CirrusSearch/wiki/Main_Page
 http://localhost:9413/CirrusSearch/w/api.php

Made possible by adding a symlink of w -> .o

Changed the MEDIAWIKI_URL and API_URL to match.

Depends on some Apache rewriting.

Change-Id: I0855e60fb53f68b98beec55e445298a2af22f0fa