Fixes #5198 - make bastion a true single page application.

This PR changes all bastion pages to be served as a single page
from / instead of multiple pages served from /katello/<resource>.
This will speed up load time between the pages (since we won't
have to reload the entire page for each Bastion page).
Merge pull request #3979 from waldenraines/html5mode

Fixes #5198 - make bastion a true single page application.