Adding span support into structured text toHTML method

Copied almost verbatim out of python kit
Javascript isn't that clean yet, but functionality is there.
Still need to figure out how qunit works, until then no tests yet :/
Also added Link.web fragment type ¯\_(ツ)_/¯

This PR is very beta, but I wanted to get something that I could use put together today. Only real functionality missing now is `Link.document` links and list groups. 

Also did some whitespace cleanup, hope you don't mind.