Add Store.expectChangeListener

Signed-off-by: Jesse Stuart <jesse@jessestuart.ca>
Add optional `beforeHandler` hook to Router instances

Called before handler:before event is sent through dispatcher

Also adds `handler.router` property to handler:before event

Signed-off-by: Jesse Stuart <jesse@jessestuart.ca>
Fix: route pattern params are included in handler:before event

Signed-off-by: Jesse Stuart <jesse@jessestuart.ca>