Test adapter

This is useful for testing standalone scripts. It has a simple array to capture responses availables as `#history`.

It looks like this in your tests.

```coffeescript
Path  = require("path")
Robot = require("hubot").Robot

pkg = require Path.join __dirname, "..", 'package.json'
testAdapter = Path.join(__dirname, "adapters")

Version = pkg.version

describe "The Hubot Script", () ->
  robot = null
  beforeEach () ->
    robot = new Robot testAdapter, "test", false, "hubot"
    robot.loadFile  Path.join(__dirname, "..", "src"), "script.coffee"
    robot.run()

  afterEach () ->
    robot.shutdown()

  it "displays the version", () ->
    robot.adapter.receiveText("hubot deploy:version")
    expected = "hubot-deploy v#{Version}/hubot v2.7.5/node v0.10.21"
    assert.equal expected, robot.adapter.history
```
I think this only worked because hubot-deploy had this in a directory somewhere :sweat: 

`bin/hubot` is the thing that actually determines this path: https://github.com/github/hubot/blob/master/bin/hubot#L73-L75