Add change events when value changes

Make is possible to watch a P&T Switch for changes. The `change` event requires an actual browser event initiated by the user instead of via javascript code. By adding `.trigger('change')`, it makes it possible to watch the underlying `select` for changes.

http://stackoverflow.com/questions/4672505/why-does-the-jquery-change-event-not-trigger-when-i-set-the-value-of-a-select-us