suggestion - use cognito hosted pages instead of vue components

[gojko]

using cognito hosted web pages would make this a much better demo repository because it would:

1. show how to configure cognito hosted UI through cloudformation (not a given, the documentation is horrible)
2. demonstrate an important AWS capability
3. make the authentication code relevant for people who don't use Vue.js
4. simplify a lot of unnecessary complexity in the front end (web site)
5. possibly even add server-side analytics through cognito triggers, or show how to integrate cognito and pinpoint