mouseover/mouseenter halt the close timer

[sgarbesi]

feat

if you mouseover/mouesenter an alert, it should halt the timer, or if not halt the timer, do not hide the message until the mouseout/mouseleave event is fired?

[gandaldf]

I added a non-intrusive solution here: https://github.com/gandaldf/angular-growl-2/commit/fab9bd0721ba6c45895f28172edb41e6d2446f94