Added possibility to show tooltips on init at once, not only on hover event

I decided to use your plugin for validation hints in contact form, but I didn't know that it works only on hover.
I refactored your code and added the new feature, so if you choose to merge my fork, it would be nice to add description for new setting 'alwaysVisible' in documentation on your site.

Also I took the function animateOut() to an external "API". So we can hook the hidding tooltips from external function without using chaining. In my case I needed it to remove tooltips before resubmit form by AJAX.

Easy to use:

```javascript
// only first argument is obligatory
tooltipster.animateOut( tooltipToKillAsJQueryObject, animationSlideOrFade, speed  );
```