Kit::Auth - Add 2steps auth

[nathan-appere]

Todos

• Add logic with tokens
• Add web views
• Add APIs call
• Add web admin actions / views

Notes

• Through authenticator app ref
• Through SMS ?
• Through email ?
• Add recovery codes ?

Refs

• https://github.com/ankane/lockbox
• https://github.com/mdp/rotp
• https://github.com/tinfoil/devise-two-factor
• https://coderwall.com/p/qw7hwq/effortless-two-factor-authentication-in-rails