~/.stormpath/apiKey.properties is not loaded

Reproduction situation:
- No environment variables are defined
- The file `~/.stormpath/apiKey.properties` does exist, with these contents:

```
apiKey.id = xxx
apiKey.secret = xxx
```

But the following construction fails:

```
var client  = new stormpath.Client();
```

With this error:

```
Error: API key ID and secret is required.
```

This may be a duplicate report of #6
