Add store.js

Store.js is a wrapper around localStorage and tries
to fall back to some other HTML5-ish storage
mechanisms before giving up and doing nothing.
Add session service

Add a session service to our Angular app,
basically a singleton we can pass around
that doesn't expire for 12 hours (on a
rolling basis).
Session: Save signed-in user

When we sign in, save the user to our
localStorage session.

Add the ability to sign out.