Allow inserting HTML raw code inside the span

[alexnm]

I see a lot of cases where you need to format your text inside the tooltip and html formatting is the closest to the react way I think. This way you can specify the tooltip text as raw html: "

This is a tooltip

"

[wwayne]

This may be a method to support html format content, but in this pull request, user will get [object] when they just provide content like data-tip='tooltip'.

We may need a better way to implement this(make this as an option perhaps)
Anyway, you've provide a good way to implement this, thanks

[alexnm]

yes, I agree, an option would be great. If I have time I might try a more generic approach and do another pull request.