Added actions `select-value`, `add-value`, `remove-value`
Added actions `select-value`, `add-value`, `remove-value`

These "value" actions- similar to their "item" counterparts- emit the selection _value_ as specified by the component's `optionValuePath`.

The aim is to provide an easier way to conform to the data-down-actions-up methodology.

Updating a target property can be done with a simple `{{mut}}` helper or other, without needing to create a specific handler to parse out. a specific value from a passed object.
kevinansfield/ember-cli-selectize,dortort/ember-cli-selectize,grapho/ember-cli-selectize,miguelcobain/ember-cli-selectize,RuslanZavacky/ember-cli-selectize,enderlabs/ember-cli-selectize,AW-UC/ember-cli-selectize,david-duncan/ember-cli-selectize,AW-UC/ember-cli-selectize,dortort/ember-cli-selectize,miguelcobain/ember-cli-selectize,kevinansfield/ember-cli-selectize,david-duncan/ember-cli-selectize,twig1337/ember-cli-selectize,RuslanZavacky/ember-cli-selectize,enderlabs/ember-cli-selectize,Keeo/ember-cli-selectize,twig1337/ember-cli-selectize,grapho/ember-cli-selectize,Keeo/ember-cli-selectize