Pasting with mouse right-click doesn't activate 'Insert link'-button

In the linkit-dialog, when you paste a link with the mouse (right click in the Link-url field and then paste), the insert link button is not activated.
This is because the field only triggers a requiredFieldsValidation on a keyup-event.

Simple fix would be to also bind the 'input propertychange'-event. Perhaps even the paste-event.
Down side of the paste-event is that it also triggers on keyboard-pastes, which also triggers a keyup-event.

My patch only binds the 'input propertychange'-event.

I've tested (on xubuntu) in latest Firefox, Chrome and IE9 and IE10 (win7 virtual box)