Added Minitest framework

Also added tests for User and LoginController
Separate authentication into a backend class
Reuse Katello logging in SSO
Secret token is randomly generated

It can be stored in yml config file or in configuration file in /etc
so cookies are not invalidated after server restart.
Integrate Alchemy UI

Main reason why not to use alchemy login layout is that we need form
without AJAX. Redirects would not work in such case. Also we need just
one form atm.
Added support for session expiration

You can now specify a life of username cookie and session. Cookie does
not contain any sensitive information and makes just login process
easier for user. It's used as default value of username input.

You can also set session expiration. By default application will log you
off after 10 hours of inactivity.
LDAP support

Added new authentication backed that uses ldap_fluff gem. This brings
support for authentication against OpenLDAP, FreeIPA and AD.
Rename application, SSO was to generic name

New name is Signo.
Support for HTTPS setups