TransitUIWebViewContext must unbind from webview on dealloc

[HBehrens]

at TransitUIWebViewContext dealloc doesn't reset the original delegate to the webview. Something like this should be better:

-(void)dealloc {
    [self unbindFromWebView];
}

-(void)unbindFromWebView {
    [_webView removeObserver:self forKeyPath:@"delegate"];
    _webView.delegate = _originalDelegate;
}