Updated app config and added mocked model.
Added mocked models.
Added mocked models.
Added mocked models.
Merge branch 'develop' into docs_trib_app_mocked_models
Added middleware to get the request context so that the app can use the selector to choose mocked models.
Updated contextualizer for trib app.
Added middleware and updated app configs so that apps use mocked models by default.
Changed the middleware so that the app uses live data by default and mocked data when the query string  is appended to the URL.
Updated the trib app to use live data by default and use mocked data when the query string parameters  is appended to the app URL.
Adding middleware and mocked models.
Merge branch 'docs_trib_app_mocked_models' into devguide_exs_add_mocked_models
Merge pull request #1278 from zhouyaoji/devguide_exs_add_mocked_models

[examples] Added middleware and updated app configs so that apps use mocked models by default.