Added Oauth2 from a web application
Added Oauth2 from a web application

New AuthType and the ability to set an oauth token - as per the following excerpt.  Your code will have to take the steps necessary to get the OAUTH token an example can be seen [in this issue](https://github.com/tan-tan-kanarek/github-php-client/issues/75)
```
        $client = new GitHubClient();
        // The following two methods are new additions
        $client->setAuthType( 'Oauth' );
        $client->setOauthToken( $oauth_token );
```
coldfire79/github-php-client,tan-tan-kanarek/github-php-client,jlhags/github-php-client