Added ability to specify a CSS querystring parameter in addition to url parameter.

[xicubed]

added the ability to specify css styles in the querystring parameter … … …"css".

• refactored documents css from index.html to essay.css
• copied essay.css to alt.css just to give me somewhere to test and changed the body background to beccapurple (#663399).
• to test the alt.css append this querystring parameter to a working myword instance: ?url=https://dl.dropboxusercontent.com/u/36518280/misc/myWordDemo.json&css=./alt.css if no css is specified it defaults to essay.css. of course ./alt.css could be a fully qualified url or any url for that matter anywhere.