Use localStorage to manage the authentication status if the user

[jgreben]

Fixes #316

On the HomePage it checks whether the user is authenticated in redux; if not, it will look for the JWT query param and authenticate them. When the component updates it will then save the authentication state to localStorage via the saveState() call.

The LoginPanel, Editor, and other child components then look for the authentication state via the loadState() call and set their local state accordingly.

The HomePage logOut() function gets passed to the LoginPanel child component (other child components will need it later) and when called it clears the localStorage state and then redirects to cognito for the destruction of the JWT.

[jermnelson]

LGTM; one question, is there a way to set a timeout for the jwtAuth stored in LocalStorage?

[coveralls]

Coverage decreased (-0.9%) to 79.132% when pulling c48debb on store-jwt into 0db4552 on master.

[jgreben]

@jermnelson I added a timeout check to localStorage.js. When the loadState() function is checked, it will return undefined if the timeout set in the jwtAuth hash has passed .