Use relative-paths instead of named modules

Named modules make our code [less portable](http://requirejs.org/docs/api.html#modulename) and are usually used by optimization tools. [Relative paths](http://requirejs.org/docs/api.html#modulenotes) seem to be made exactly for our use-case:

> Relative paths are really useful if you are creating a few modules inside a directory, so that you can share the directory with other people or other projects, and you want to be able to get a handle on the sibling modules in that directory without having to know the directory's name.

This approach is better than named modules because we won't have to add a named `path` config for every module we want to include in our main app.