People Picker Widget support for filtering suggestions

Ability to define callback function on input that can be used to filter list of suggestions retrieved from the server.
(In support of Issue #25)
SPFilter Panel Support for Sort Order and fixed height

- SPFilter panel now supports setting a fixed height.
- SPFilter Panel now supports setting the sort order on each column.
- Updated Demo and documenation to reflect chagnes done
- updated plugin with latest chagnes.