Minor updates to Tor config

1. Enable scramblesuit plugin for obfsproxy. This should now work correctly with the new version of tor (0.2.5 currently in unstable).
2. Enable ExtORPort for local communication between tor and obfsproxy. This socket is bound to localhost and used for gathering statistics. (This thread has some details: https://lists.torproject.org/pipermail/tor-relays/2014-February/003908.html)