Added PocketTest app

It uses WebView to authenticate, avoiding an ugly flash at each startup. But it's against Pocket's API guidelines, which say:

Please send the user to the URL via their default browser in a new tab; do not present this page in a webview or screen within your application. Doing so violates Pocket's API guidelines. If you feel like your app should have an exemption, please contact us at api@getpocket.com with your request.