Update gems to prevent oauth redirect loop of death

Unauthenticated users are currently unable to log into Play (including me :frowning:), returning an infinite redirect :loop:  (locally), or a 502 bad gateway (server).

Update `sinatra_auth_github` to the latest version, update `Gemspec.lock`, and a small tweak to match `sinatra_auth_github`'s new API.

Also, `realtime.rb` errs out with [a missing require](https://github.com/benbalter/play/pull/new/master#L3L9), *see* https://github.com/play/play/issues/228.

I commented out for now, and things seemed to work fine.

Testing locally and was able to Oauth just fine.