Receive benchmarks from runners

A runner can send details of it's benchmarks scores to the API to: ```POST /api/v1/results``` with the data in the request body in json format such as:

```
{
  "run":{
    "ruby_version":"2.0.0-p247",
    "git_hash":"c0a04be8ddcadcd89c02bc135e4b288f6d936704",
    "date":"2013-12-18T12:09:16+00:00",
    "results_attributes":[
      {"benchmark":"some_bench","score":"222"}
    ]
  }
}
```

In addition to this you need to send the header ```Authorization: Token``` which should contain the token of the runner that is sending the results. You will need to create this runner first (no UI for this yet).

Take a look in the readme for more details and a cURL example. The specs also detail the behaviour.

Feel free to send any comments, I won't merge this until at least someone else has reviewed it.