react-native-router-flux navigation

Many thanks to @wookiem !!!! for #75 & #74 and who provided the code and the notes below

1. Define navigation schema and routes in the snowflake.js file. This also allows you to define the animations during view transitions.
2. Replace Snowflake's Tabbar implementation with built-in version from RNRF. I was able to add Tabbar icons using react-native-vector-icons.
3. Modified app.js to navigate directly to Register (or Login) after startup.
4. Navigate using "type: replace" to Tabbar screen after registration/login. This ensures that Tabbar is now the root in the navigation tree.
5. Navigate back to Register (or Login) using "type: replace" when user logout.
6. Separated Snowflake's single Login container into 3 separate containers (i.e. Register, Login and Password) which in turn calls a common rendering component. I found this was necessary because after user does a successful Register or Login, there is an extra render on the Login module in the "LOGIN_STATE_LOGOFF" state which temporarily flashes a slightly different render screen before app.js calls the Tabbar.js container.
7. Added a "Main" container and "Subview" component to provide examples of navigation within the main application.