Rails 5 Support

[AjayBarot]

#168

@pencil @luxflux : Please review this code. Most of the spec fix by adding this gem. and still to many DEPRECATION WARNING exist and some specs still failing. Any idea why this specs failing ?

1) CASino::ProxyTicketsController GET "proxy" with a proxy-granting ticket without a targetService answers with the failure text
2) CASino::ProxyTicketsController GET "proxy" with a proxy-granting ticket without a targetService does not create a proxy ticket
3) CASino::SessionsController GET "destroy_others" with an existing ticket-granting ticket redirects to the session overview
4) CASino::SessionsController GET "new" with an unsupported format sets the status code to 406

Thanks