Updated docs

[ahumphreys87]

new doc generation. Lots of changed files, I have removed the duplicated assets from each version of the docs, they now all point to a central location.

• Added active class to current page in sidebar. Fixes Add an active state in the left menu for each doc page. #47
• Added index page to root of docs/ and each version root. Fixes Create an index.html.md for the docs #56
• Added 'Improve this doc' button and a link to the source file. Fixes Add a "edit on github" button to the doc pages #48
• Added select version dropdown to jump between versions of docs. Fixes Add a select dropdown to jump between versions of the docs  #49

[samccone]

Updated a few things and merged into master!

Thanks @ahumphreys87 !!!