Landing page

@brettjohnson I got started. Look at the files changed to see how it works.

What I did so far:
* I ran `mrt add leaflet` to add the [Leaflet](https://github.com/bevanhunt/meteor-leaflet) smart package. This changed `.meteor/packages`, `smart.json` and `smart.lock`
* I created the `index` template (http://localhost:3000/ opens it because the path `/` was already mapped to `index` in `client/base.coffee`)
* I did some styling in `client/css/main.less`. I call it the *MTA aesthetic*.