Ability to run integration tests locally

I have problems getting saucelabs to run our test suite (it was added by @jharding in twitter/typeahead.js project back in 2014, but broke at some point in time).

Now, some of the problem is covered by #20 and #21. But actually being able to run the integration tests locally would help so that we can see and debug errors with the actual suite.

The file `integration/test.js` is the actual test, but also sets up Saucelabs-specific variables.

The task will be to make a split, so that we can run a simple task locally (which probably could use Phantom).

For example:

```
npm run test:integration
```