A few changes as per today's meeting:

* Get rid of login (and logout) by ajax. Use the modal, but do a
  normal form submit so that the page is refreshed properly.

* Bug fix for - and _ not working in Firefox/Shellinabox window; thank
  you google search.

* Fix for NaN dates on Firefox. Turns out Javascript Date() is not
  rfcwhatever compliant. Too funny.

* Fix permission check that was allowing guest user to see and use
  someone else's experiments.