Error Message when file upload is too large

Noticed a JavaScript error in IE9, which was caused by the call to
requestAnimationFrame in loader.js. Added client side checking of spaces on room name when creating a new room (fix #1191). Added custom error message for when a file upload is too large (fix #1190).
Good catch.  We need something here to deal with invalid room name entries (anything other than [A-Za-z0-9_\-]{1,30} ) when you're on the lobby screen - "a a is not a valid room name" might be what we wind up with for this eventually...