[W3C]Page not validated if a tooltip is used

[simonepri]

This is the incriminated line:
https://github.com/720kb/angular-tooltips/blob/master/dist/angular-tooltips.js#L760

I saw that that ID is not used for anything so I think it can simply be removed or replaced by:

closeButtonElement.addClass('close-button');

[45kb]

@simonepri yes that should be removed probably that's the reason why close button is no more working.... can you PR? 🚀

[45kb]

#193