Documentation url in jsondoc-ui.html parameters

[fabiomaffioletti]

This is to avoid typing every time the jsondoc url in the top bar box. If the url query parameter is populated, then the documentation is automatically fetched and displayed. Something like this:

http://localhost:8080/jsondoc-ui.html?url=http://localhost:8080/api/jsondoc

Enabling the documentation writer to communicate the whole url, ready to be used by the documentation readers.