testling support

To close #233.

Just following the [quick start guide](https://ci.testling.com/guide/quick_start).  Only thing you'll need to do is [add the web hook](https://ci.testling.com/guide/quick_start#configuring-the-web-hook).

Unfortunately it looks like the [build is failing on my fork](https://ci.testling.com/lkptrzk/joi), but that matches the output I got running locally on my mac opening the tests in chrome:

```bash
~/git/joi> browserify test/*.js | testling -u # -u flag prints url to visit in browser
http://localhost:50349/__testling?show=true

not ok 1 Error: Uncaught TypeError: Object #<Object> has no method 'createDomain' on line 15420
^C~/git/joi> browserify test/*.js | grep Domain
var Domain = require('domain');
    var baseDomain = Domain.createDomain();
    var scopeDomain = Domain.createDomain();
            baseDomain.exit();
            scopeDomain.removeAllListeners();
    scopeDomain.once('error', function (err) {
    baseDomain.enter();
    scopeDomain.enter();
```

Looks like @substack's already on fixing that via [this pull request in the browserify shim for domain](https://github.com/bevry/domain-browser/pull/1).