Trigger `change` event when value is selected

[mhamann]

Presently, it seems that the only way to get a notification when the value of the select view changes is to provide an update method on the parent view. This doesn't work well for a view that has multiple select fields or that wants to follow an orchestrator pattern where the child view knows nothing about and does not attempt to call methods on its parent.

We should provide a change event trigger whenever setValue is called.

[wraithgar]

Seems reasonable, and wouldn't take too much to add.

It could be a little cleaner and easier to see what's happening if the trigger happened in the onChange function right after setValue is called, but this is admittedly bike shedding.

Is this something you're comfortable making a PR for, with a test?

[mhamann]

Yep, I can do that. Will try to set aside some time next week to get it written...