Feature: Route guarding

[soniaroh]

Implemented private routing for "/order" and "/view-order" routes.

• created a PrivateRouter component that conditionally returns a route that checks if redux store's token has a truthy value
• in the case that user is not logged in, the falsy token redirects the route to /login page
• AppRouter component is connected to the store, so it can read the value of token and render routes accordingly.

closes Shift3#21