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.
Refactor TBB firefox start into exec_firefox() library function.

That way one only has to remember to always call firefox with
exec_firefox(), and not to set LD_LIBRARY_PATH. As an example, this
was forgotten for Tor Launcher, which also was fixed.
Add --pause-on-fail to ease VM state debugging when tests misbehave.
Add execute_successfully() and assert_vmcommand_success().

In many tests we execute VMCommand:s without checking the return
status, assuming success and that the stdout we get is fine. In some
cases this assumption could potentially result in a test passing when
it should not.
Test that the Tor Browser uses the expected shared libraries.
Update test suite image for Firefox esr31 bump.
Add workaround for showing the browser's menu bar.
Mention that the Tor Browser needs the TBB's bundled shared libs.
Mention that the Tor Browser is used as the basis for the Unsafe Browser.
Adapt Tor Browser's IE theme for the esr31 upgrade.
Properly localize the Tor Launcher.
Clean up pgrep's regex and use long option names.

The anchors were supposed to be removed after adding -x/--exact.
Make 10-tbb hook executable.
Make 14-add_localized_browser_searchplugins hook executable too.