[CLC-1765] Custom URLs to get around unrecoverable 404 problems
- Capybara(selenium) test for url validation
- Making headless run more robustly

- headless fixes
- use a non-interferring xvfb port with current hardcoded bamboo one

Note: the headless gem should help clear up some of the temporary jasmine CI tests on bamboo instead of trying to kick off Xvfb manually in a bamboo script. Should open a ticket to investigate