First rudimentary POC version

I haven't yet made it Pathogen compatible. Heck, it's not even a vim
plugin yet. But it works, at least for a very basic requirement. Here's
how to use it:

  In vim, place your cursor on a variable to require. Here's a jsx
  example:

     <Button/>

  Make sure that a file components/button.js.jsx exists.

  Type
    :rubyfile <path_to:vim_import_js.rb>

Notice how this gets added to the top of the buffer:

  var Button = require('components/button');

Simple as that. Next up:
  - Only add imports that don't already exist.
  - Handle ambiguous cases
  - Make it a vim plugin, Pathogen compatible