Implement "My Apps" support using the MyApps plugin, not the "apps" command.

The "My Apps" plugin returns apps that have been installed via
mysqueezebox.com, which appears to match the behaviour of other remote
control apps and the web UI on the server.

- The individual apps are returned as plugin items, so adjust the classes
  that ApplicationListActivity and ApplicationView inherit from.

- Add a new MY_APPS plugin type to request and manage the information.
Track whether the server supports "Favorites" and "My Apps".

- Add handshake tests for "favorites" and "myapps" support.

- Store this information in the ConnectionState.

- Use it to control the item visibility in HomeActivity.