[CLC-1765] Custom URLs to get around unrecoverable 404 problems 

JIRA: https://jira.media.berkeley.edu/jira/browse/CLC-1765
JIRA: https://jira.media.berkeley.edu/jira/browse/CLC-1762

- 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