Trigger 'didRetrieveSuggestions' event when autocomplete suggestions fetched

Instead of setting `allSuggestions` property directly
Refactored autocomplete and tags views to better support autocomplete with tags view

In autocomplete:

* Search for autocomplete suggestions using an arbitrary string (not just the `search` property)
* Don't autocomplete on blur if the input value isn't as long as the min length for making suggestions

In tags:

* More means to override tag acceptance and addition methods

In autocomplete with tags:

* Added `autocompleteThreshold` property to allow basic configuration of if and how strictly new tags are autocompleted (useful if the user pastes a value into the field)
* Some additional tag addition/rejection events and handling