HTML Javadoc

Hey Jim,

Notice that I had to update a param from `text` -> `html` in the `HtmlImpl` class. We had discussed how the `Html` class was the example to follow for variable names, but that most changes were needed in the `HtmlUtil` class.

Now all variable names are synced with the `Html` interface, and all Javadoc reflects these changes.

https://issues.liferay.com/browse/LRDOCS-939