deposit: conferences typeahead requirejs impr.

Some fixes of conferences typeahead regarding requirejs. It was working anyway, but now it works better ;)

depends on: https://github.com/inveniosoftware/invenio/pull/2277
It is used in lines 49 and 55.

The Bloodhound export is not really needed from practical point of view. Once you require 'typeahead' Bloodhound is loaded to the global scope, and is somehow visible in this file. However from formal point of view it should be there cause 'typeahead' exports it and ConferencesTypeahead needs it.