Hide address bar

Added a feature to hide the address bar.

```
    // Method for showing controller with completion block
    controller.hideAddressBar = YES; //hides the adress bar
    [controller showControllerWithCompletion:^(JBWebViewController *controller) {
        // Completion typedef block
        NSLog(@"Controller has arrived.");
    }];
```

I need this in a project where I want to show terms and conditions pages. In this case it is useful to hide the address.