Open the tooltip if only data-tip-html is present.
Make the tooltip implicitly use the "title" attr.

If no "html" or "text" option is provided, either
through data attributes or constructor options, the
tooltip check if the "title" attribute is present
and uses as the tooltip content.
Merge pull request #220 from dcruz/develop

Tooltip implicitly used the "title" attribute if no "text" or "html" option is provided