Fix localization of the Unsafe Browser's name-setting.

It turns out that the branding's name of the browser can differ quite
a bit between different langpacks, e.g. in Arabic it's written in
Arabic, but in languages using latin based it's often "(Mozilla)?
Firefox". Hence we must set the value according to the key, which is
the saner way, instead of simply replacing values.
Fix automated test suite for migration to TBB.

Beyond s/Iceweasel/Tor Browser/ (incl. renaming affected images) we
also try to rely more on clicking on GUI elements instead of keyboard
shortcuts. The TBB is noticeably slower on start, and often loses key
presses at that stage, so clicking is much more reliable then.

The most remarkable change may be the switch to the step "the Tor
Browser has started and loaded the startup page". It seems a fair
amount of complexity is required to reliably stop the loading of the
startup page so this simpler approach seems better, and as a bonus it
actualy tests the startup page. The issue described in the removed
comment doesn't seem very relevant any more, too.
Migrate to TBB 4.x.

Note that the browser profile has been moved location inside the
tarball, and the bundled firefox will look for the default profile
accordingly.
Set Unsafe Browser camouflage after ownership change.

The Unsafe Browser camoufalge was broken since the browser profile was
owned by root, no the user running the tails-activate-win8-theme
script, which require that it is writable for that user.
Explain a bit more why we split the TBB like we do.
Improve comment.
Set the TBB installation paths in its own shell library.
Set missing executable bit in scripts.
Translate the tor-browser script.
Make script more robust.
Look for omni.ja in the correct place.

TBB_EXT was a typo.
Disable cups in the unsafe-browser

This will prevent the browser from hanging for several minutes will
trying to contact CUPS if a user accidentally presses CTRL+P or tries
to go to File -> Print.

Adapted from patch sent by Kill Your TV.