Typeaheads with default value don't display choices on select

[aamccaslin]

There's a bug either in our dynamic choices or the uib-typeahead. If the schema has a default (null or value) then focusing the typeahead does not display the choices until a key is pressed

Once a key is pressed the behavior is as expected.

It looks like an empty list briefly flashes on render, that could have something to do with the problem. May also be related to the template filtering on $viewValue.