Route to new SignIn page.
Add omniauth-identity authentication.

It enables users to register and sign in, this fixes #3.
Add and install devise.
Add required models and routes.
A working devise login.
Remove identity related files.
Remaining files of identity
Fix specs.

Fix controller specs after devise.
Use bootstrap in devise views.
Add mail address for devise.
Merge branch 'multiple_providers'

Fixes #3