Refactor the new, pretty, autocomplete code (preparing to move it to

Refactor the new, pretty, autocomplete code (preparing to move it to
Horde's scope):

- Don't force client code to constrcut the DOM structure need for this to work.
  All we need to do is add a single input element, and attach it to the autocompleter.
- Allow overriding of CSS Classes and DOM ids used to allow for mulitple scopes/multiple
  autocompleters on the same page.