Revamp APT pinning for the Tor project's APT repositories.

Install:

  * ttdnsd from their unstable repository (it's not distributed through the
    Wheezy one)
  * Tor from their Wheezy repository (with higher priority than the official
    Debian repositories, to match what we are doing in the Squeeze images)
  * other packages from their Wheezy repository, at APT's liking (pinned to 990,
    like the official Wheezy and wheezy-updates repositories)

config/chroot_apt/preferences

@@ -162,11 +162,15 @@ Pin: release o=Tails,n=feature-wheezy
 Pin-Priority: 1010
 
 Package: tor
-Pin: origin deb.torproject.org
+Pin: release o=TorProject,n=wheezy
 Pin-Priority: 999
 
 Package: tor-geoipdb
-Pin: origin deb.torproject.org
+Pin: release o=TorProject,n=wheezy
+Pin-Priority: 999
+
+Package: ttdnsd
+Pin: release o=TorProject,a=unstable
 Pin-Priority: 999
 
 Explanation: override deb.tails.boum.org's Squeeze -specific package.
@@ -250,7 +254,11 @@ Pin-Priority: 990
 
 Package: *
 Pin: release o=Debian,n=wheezy
-Pin-Priority: 900
+Pin-Priority: 990
+
+Package: *
+Pin: release o=TorProject,n=wheezy
+Pin-Priority: 990
 
 Package: *
 Pin: origin backports.debian.org
@@ -263,3 +271,7 @@ Pin-Priority: -1
 Package: *
 Pin: release o=Debian
 Pin-Priority: -10
+
+Package: *
+Pin: release o=TorProject
+Pin-Priority: -10