[apparmor] Let's enable AppArmor by default (why not?)

[intrigeri]

Hi,

intrigeri:
> The next upload of the linux-image packages will "Recommends: apparmor".

Done ⇒ AppArmor is now enabled by default in sid.
Let the experiment begin!

Now is time to report and fix bugs. To make sure they are on the radar
of the AppArmor team, please apply the relevant usertag:

  https://wiki.debian.org/AppArmor/Reportbug

Thanks in advance, and sorry for any inconvenience it may cause (e.g.
the AppArmor policy for Thunderbird has various issues in sid; all of
those I'm aware of are fixed in experimental already).

Cheers,
-- 
intrigeri