base: move of remote autocomplete field

* Moves the script for autocompletion from groups module to
  base module.

* Refactoring the script as a RequireJS module that returns
  a FlightJS component.

* Adds documentation on how to use it.

Signed-off-by: Leonardo Rossi <leonardo.r@cern.ch>
and for javascript `.. code-block:: javascript`? :)