Planned Arch Cookie Cutter updates

Best practices / quality of life:

• Flatten src directory structure with READMEs that explain what belongs where:
  • actions
  • config (store configuration, environment, api client)
  • constants
  • components
  • effects (side effects, thunks, sagas)
  • reducers
  • selectors
  • services
• Combine containers and components (we're misusing the concept a bit and it creates more file navigation friction...)
  • https://medium.com/@dan_abramov/smart-and-dumb-components-7ca2f9a7c7d0
  • It's not that the container is the thin wrapper around a component that connects it to redux, it's that the connected components should be considered containers where communication with the greater ecosystem are concentrated.  Let people add a containers directory if they have enough of them that it helps to split it out - don't start under that presupposition. 
• Convert index.jsx files to files named for their contents.
  • Sub-components in directory named for the above component.
  • .test.jsx and .messages.jsx files as peers of their component.
• Separate dev and prod redux store configurations in config directory.
• Add codecov to .travis.yml
• Webpack config updates (misc)
• Application structure readme (How do I structure a frontend app with unidirectional data flow so it stays organized?  What goes where, how should I think about it?)

Test/code examples (maybe as gists linked from the README?)

• Component snapshot testing
• Component enzyme assertion testing
• Connected component testing
• jest.mock() examples
• jest.spyOn() examples
• redux reducer tests
• Selector (mapStateToProps) tests
• redux-thunk tests
• redux-saga tests
• Service / side effect tests
• Cypress tests - https://github.com/edx/cypress-e2e-tests
• Action tests
• Usage of paragon components with redux-forms

Issues to address:

• https://github.com/edx/front-end-cookie-cutter-application/issues/61 - Upgrading font awesome 

• https://github.com/edx/front-end-cookie-cutter-application/issues/82 - Using terser instead of uglify-js

Packages to use (most of these don't exist, but maybe should):

• frontend-analytics

• frontend-auth

• frontend-i18n

• frontend-logger

• frontend-api OR example services

• Generic error/exception messaging (500 errors, etc.)

• paragon (usage is shifting soon with working group changes)

• edx-bootstrap (usage is shifting soon with next major version)