you have to add the sfOAuthPlugin https://github.com/chok/sfOAuthPlugin
to your project for the missing libraries to be autoloaded. If you download the zip file from GitHub, make sure to also download the OAuthBase https://github.com/chok/OAuthBase
repo as it is a git submodule..
I'm setting up the same today and run into similar issues.
Other issues encountered:
- error message about the access_token (solved by making the callback route in app.yml equal to the login route
- problem with the user retrieval based on email_address which belongs to the sfGuardUserProfile table (not completely solved yet, I'll add a pull request to the sfMelodyPlugin when done.