Failed to access through accessToken

Maybe I understand wrongly the utility of the accessToken (first argument returned by the callback when creating the strategy) because when I am trying to sign in it does not work correctly:

```javascript

var github = require('octonode');

passport.use(new Strategy({
clientID: clientID,
clientSecret: clientSecret,
callbackURL: callbackURL
},
function(accessToken, refreshToken, profile, done) {
var client = github.client(accessToken);
// Client is not signed in...
}
```

Start at the Strategy callback shown in the issue and reproduce the accessToken flow with octonode's github.client(accessToken). Check whether the resulting client can authenticate a GitHub API request. Done means the token returned by the callback provides an authenticated client, or the issue documents the required token handling and its limitations.

Written by the indexing model from the issue text.