add multi hbs template and 'view all on one page' links + page

this adds a 'view all on one page' button to the sidebar nave and the frontpage table of contents.

it also adds a new 'multi.hbs' layout that renders multiple pages at once with an optional page heading.

I am not an experienced express, handlebars or stylus user so apologies if I did something wrong

Also I didn't really style the links that much, feel free to move stuff around. I mostly just want a 'view all on one page' button so I can search all the docs with CMD+f in my browser.

![screen shot 2014-11-01 at 12 27 52 pm](https://cloud.githubusercontent.com/assets/39759/4871651/c6f9e27a-61c2-11e4-9466-218daa4b9f98.png)

![screen shot 2014-11-01 at 12 28 43 pm](https://cloud.githubusercontent.com/assets/39759/4871655/e479b0e6-61c2-11e4-9fde-c6f6626a11e0.png)