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"
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.
Clearer POD.
Support DISABLE_PROXY in tails-security-check for easier testing.
Make it clear that we may not provide IUK's for major releases.
Drop PENDING marker. When this branch is merged, this stuff will be on by default.