Patched tor and jtorctl for improved hidden service performance.

Two changes have been made to Tor:

1. Set can_complete_circuit to false when the network is disabled, and
don't try to build introduction circuits while can_complete_circuit is
false. This avoids a situation where Tor tries to build introduction
circuits as soon as the network is re-enabled, all the circuits fail,
and then Tor waits 5 minutes before trying to build more.

2. Added a FORGETHS command to the control protocol which clears any
cached client state relating to a specified hidden service. This can be
used to flush state that's likely to be stale before trying to connect
to a hidden service with an unstable network connection.

Support for the FORGETHS command was also added to jtorctl.