Inefficient, causes way too much traffic and takes very long

Also show a spinner when logging in (to disable resubmitting login form)
and when refreshing the available chatrooms.

- by using documentFragment

Conflicts:
	spec/MainSpec.js

Also bugfix that showed the wrong time for delayed messages.

This is so that github-pages don't ignore dirs starting with _

Makes the docs look similar to the main site

Conflicts:
	index.html

Features are saved to localStorage so that service discovery doesn't have to
happen during every request.

This was added earlier for debugging, removing it again now.