Add delegate filter autocomplete support

Add delegate filter autocomplete support

It would be helpful to provide autocomplete functionality for the
delegate filter field, similar to that provided for the submitter
field. This will provide a way to handle larger delegate lists without
overloading the user with options.

Add this functionality through use of Selectize, which is already used
to provide similar functionality for filtering of "submitters".

Signed-off-by: Stephen Finucane <stephen.finucane@intel.com>