Make tests run.

Hello!

After working in the 2.0 I decide to start porting improvements back to the 1.0 branch.

The first thing was to make the test run. I don't know why the visit with a file url was failing. So I've modified those visit with a load method.


```
NodeError: TypeError: Parameter 'url' must be a string, not object
    at Url.parse (url.js:107:11)
    at Object.urlParse [as parse] (url.js:101:5)
    at Resources._makeRequest (/..../node_modules/zombie/lib/zombie/resources.js:171:15)
    at /..../node_modules/zombie/lib/zombie/resources.js:145:20
    at EventLoop.perform (/..../node_modules/zombie/lib/zombie/eventloop.js:141:5)
    at Resources.request (/..../node_modules/zombie/lib/zombie/resources.js:144:37)
    at History._resource (/..../node_modules/zombie/lib/zombie/history.js:117:40)
    at History._pageChanged (/..../node_modules/zombie/lib/zombie/history.js:78:19)
    at History._assign (/..../node_modules/zombie/lib/zombie/history.js:271:17)
    at Browser.visit (/..../node_modules/zombie/lib/zombie/browser.js:330:25)
```

In the 2.0 there is a local webserver to make test work without internet. I'll port it another time.

Javier.