Add a CSS autocomplete class for Tickets

… and a note to the regex so that it isn't missed in the future.

This should have been part of 6375cfb.
Bestow the name of RT.Autocomplete.bind to the autocomplete registration function

Dynamically added elements can have autocomplete inputs properly bound
by calling:

    RT.Autocomplete.bind($containing_element)

after they're added to the DOM.  At some point we may want to do this
automatically, but for now manual binding is enough rope.
Merge branch '4.2/autocomplete-bind-on-demand'