Zuul: Clean up html and css.

- Whitespace
- Relative paths (so it works when testing locally from a different url)
- Drop redundant attributes
- Remove incorrect max-width on pipeline-container:
  http://cl.ly/image/0R0u0u1n0p2I
  (top: without the max-width, bottom: old version with max-width)

Change-Id: I0ddc7ceb56ebbb230c463a0367c5c454151bad1b