Make vocabulary typeahead exist on new elements

Fixes issue where typeahead would be created properly for elements
that were on the form when it was loaded, but not for elements created
via "Add subject" and similar dynamic field buttons.
Verify dynamic fields are getting typeaheads
Fix spec to wait for typeahead before clicking

Capybara should pause for a short time when we expect there to be
explicit content, so this should solve intermittent failures
Merge pull request #134 from OregonDigital/feature/make-vocab-map-live

Make vocabulary typeahead exist on new elements