Configure the Tor Browser to fallback to the filtered Tor control port.

Fallback here means if the TOR_CONTROL_PORT environment variable isn't
set. The environment variable has higher priority than the pref, and
since we set it this is just a tiny fail-safe fix.
Block the Tor Browser from accessing all local TCP service ports.

That includes CUPS, Monkeysphere, the I2P stuff, Polipo, the system
DNS, and the Tor stuff. It's every local TCP port that the "amnesia"
user has an exception for in ferm's configuration.
Drop irrelevant prefs.

We don't have the Tor Launcher extension in the browser.
Install TBB 4.x esr31-nightly builds.
Just skip localized search plugins we don't have a langpack for.

The TBB 4.x esr31-nightly we doesn't ship localized versions (from
which we extract the langpacks) for several search plugins that we
expect to have them for.

This commit should be reverted once more localized versions are
available again.
Run Tor Browser using the TBB's shared libraries.

The libstdc++6.so we have (from Debian Wheezy) is too old.