edits right before the presentation

modified:   cas_validate_2.html
modified:   css/stack.css
presentation, done and presented

posted the pdf up to speakerdeck and linked to lanyrd site
dropped spoof firefox in test

pretending to be firefox is no longer necessary with CAS 2.5.2.  Not
sure about older versions, but all tests passed without it, so it
should not be in there.

Also minor edits to cas_validate, getting rid of console.log statements
in the xml parsing code