added support for on hover notifications

[reiern70]

Hi,

For a use case we needed notifications to be closed on user hovering the mouse over the notification. So I have introduced new callback functions on settings

over: function (e. instance) {...} out: function (e. instance) {...}

that will be called when mouse is over the notification and and juts lived notification.

By default if hoverIntent.js is present (and loaded before notify.js) then hover intent will be used. If not present then default jquery hover will be used. If present but you still want to use jquery hover you can pass parameter {useHoverIntent: false}.

I have modified the sample app to show these options.