Add user ID as class to firepad-userlist-user

Assists with querying for these elements by user ID from outside of the
userlist code.
Debounce cursor activity in RTCM to fix CM 4.4+

Closes https://github.com/firebase/firepad/issues/142
Expunge morally bankrupt tabs from code
Excommunicate trailing spaces and enforce EOF newlines
Merge branch 'master' into jw-catapult

Conflicts:
	dist/firepad-min.js