First set of responsive styles

Lots of changes in here. I did my best to keep it tiny by removing as much as I could at the same time.

* Capistrano now uses `npm run-script` to compile. This frees us from needing `gulp` or `bower` installed globally on the deployment server, as they will be executed from within this deployment's `node_modules` folder.
* Body markup for pages has had 4 elements added - `#asides` to hold all of the stuff which will be put in the sidebar, `#main` for all of the other sections, `#content` to hold both of those elements, and `#hero` has a child element called .container.
* An account's recent stories has been added to the story page, below or beside the account block.
* the modal now shrinks to 500x500 on screens that are at least 600x600 - per the designs. It floats in the middle of the screen
* Asides now float to the left on larger screens

For the most part, no tweaking should be necessary of styles to match the designs we have. Provided your markup follows the patterns set here, things should flow really nicely on the page as it resizes. Generally, you should set a min-width on your `section` level elements or else they might take up the full width when it is not necessary to do so. Other than that, please let me know when you have a need to edit the CSS to make your widget display correctly so we can figure out if it is a more general style that can be extracted as a class or similar.