Creates user sign-up/sign-in with Monban

* Uses routing constraints for signed-in and signed-out
* Fixes missing secret_base_key for config/secrets.yml
* Adds landing show page when signed-out and dashboard show when signed in
* Sign-up/Sign-in links in layout/application
It should not be public, it is a HUGE security vulnerability.

See line 2, make that work.

checkout
https://github.com/bkeepers/dotenv