Add angular-typeahead
Load the angular typeahead directive.
Implement some basic type-ahead.
Add typeahead styling.
Save the category as a string.

The category is saved as a string, even if it was selected from one of the objects in the list.
The typeahead list is really just treated as a list of values used before, but there is no real
relation between the event categories at the category for the event (at least not at this time).
Merge branch 'feature/typeahead' into develop