Don't autostart iceweasel...

...but notify when Tor is ready
Uncomment tor bootstrap progress function
Warn before launching iceweasel if Tor isn't ready
Update iceweasel profile generation script
Language fixes

- Avoid using contractions
- Say "browse the Internet"
- Use "start" instead of "launch"
Fix fuzzy string.
[de] small translation
Merge remote branch 'origin/bugfix/fix-tag-existence-detection' into stable
Merge remote-tracking branch 'origin/master' into feature/incremental-upgrades
Revert "Revert "Run tails-update-frontend at session login time, after waiting for Tor to work.""

This reverts commit 5d039b3a4314e470e93a998b336b49e08ed9bb82.

That is, once the user is logged-in and Tor is working, run
tails-upgrade-frontend. This still partly duplicates the security check, stay
tuned for better integration.
Rename and adapt tails-update-frontend.desktop to match current terminology and script name.
tails-security-check: make warnings fatal.
tails-security-check: Require Perl 5.10.1 and enable its features.

There's little point in manually enabling "say" these days.
tails-security-check: Minor code style improvements, no functional change.
tails-security-check: Turn comments headings into POD headers.
tails-security-check: Drop unused version section from POD.
Update contact info.
More minor code style improvements.
Replace home-brown checks with Carp::Assert{,::More}'s ones.

Note that Tails ships lib-carp-{,assert-}perl already, as dependencies of other
packages, so this does not bloat the ISO.
More sanity checks.