Elm Example

**Early stage, keep your fingers away from that merge button!**

I tried bringing the [elm-todomvc](https://github.com/evancz/elm-todomvc) a bit closer to our spec and would like us to consider including it as official example.

Before I go on with that, I'd like to get @evancz's okay for this, though. :)

Eating our own dogfood here:

## Why Elm?

[A functional reactive language for interactive applications.](http://elm-lang.org/) I'm personally really excited about this, because it doesn't just incrementally tries to improve things, but actually rethink the entire platform from the ground up. This enables some things that are pretty much unheard of in the vanilla JS world, like a [time-travelling debugger](http://debug.elm-lang.org/) and a highly interactive development workflow with [hot code swapping](http://elm-lang.org/blog/Interactive-Programming.elm).

The project has been around for a while and is still [super active](https://github.com/elm-lang/Elm). There are a couple of TodoMVC implementations floating around, but this one is especially interesting because it brings the virtual DOM ideas to Elm. Here's a nice article describing this in depth: http://elm-lang.org/blog/Blazing-Fast-Html.elm

## Outstanding Issues

The layout is a bit buggered right now, I'm not quite sure why. I need to read a bit about Elm's full screen rendering mode. I also haven't run the test suite yet. I'm sure there'll be a couple of edge-cases that haven't been covered yet.
Would be more in line with the other examples, but it's a naming clash with the built-in function and reduces the readability. Current code example: `(map todoItem (filter isVisible tasks))`