Add logout flow

[janet]

• adds global app reducer and saga for logout (next incorporate with login and resetpassword)
  • changes routes.js to have all components become a child route of app using solution from https://github.com/react-boilerplate/react-boilerplate/pull/1545
• adds app actions, constants, reducer, saga for logout (next incorporate with login and resetpassword)
• adds app bar
• redirects to /login if not logged in

[janet]

closes #25