Integrate AuthSCH login

Basically copied from schorpong project
Integrated AuthSCH with Omniauth gem.
Added helpers to get if user is logged in, and to get user: example usage can be found in _nav.html.haml
Added user scaffold with basic fields, authorization may need extra fields in the future.
Added example .env file and some description in Readme.md
Designing user views will be another issue.

closes #13

kir-dev / konyha