Update README to mention that we're borrowing code from rubycas-server:
Update README to mention that we're borrowing code from rubycas-server:

nbudin/cassy,backupify/cassy,nbudin/cassy,OneHQ/cassy,OneHQ/cassy,reinteractive/cassy,backupify/cassy,OneHQ/cassy,nbudin/cassy,backupify/cassy,reinteractive/cassy