heka experiment

Ok, there's kind of a lot going on here. Basically this gets us using heka for process memory tracking via statsd, and sets up the awsbox and local environments for heka.

The full list of changes:

* Use a new AMI with heka preinstalled
* On the awsbox instance heka runs under the `app` user and is (re)started in the `postdeploy` hook
    * this is to pick up changes to `heka/hekad.toml`
* `npm start` now also runs heka
    * **this assumes you have `hekad` installed somewhere in your `$PATH`**
* `heka/hekad.toml` is configured to
    * listen on UDP 4880 for heka messages
    * listen on UDP 8125 for statsd messages
    * listen on TCP 5565 for sandbox admin
    * log all incoming messages to stdout
    * process statsd messages with `memory.lua` plugin for graphing on the dashboard
    * host the dashboard on http://localhost:4352
* `spumko/good` ops metrics are sent to heka via statsd through `lib/stats.js`
    * wired up in `server.js`
* `memory.lua` uses a circular buffer to store 1 hour of memory stats in 15 second increments from the statsd input
* `scripts/hekad.sh` is a sample init.d script that isn't in use yet, but could be a starting point for a production heka install.