Install Linux and related packages from Wheezy.

Debian sid just got Linux 3.8, and we don't want to switch to a new kernel just
a few days before Tails 0.18 is released.

config/chroot_apt/preferences

@@ -212,15 +212,15 @@ Pin: release o=Debian,a=unstable
 Pin-Priority: 999
 
 Package: initramfs-tools
-Pin: release o=Debian,a=unstable
+Pin: release o=Debian,n=wheezy
 Pin-Priority: 999
 
 Package: klibc-utils
-Pin: release o=Debian,a=unstable
+Pin: release o=Debian,n=wheezy
 Pin-Priority: 999
 
 Package: libklibc
-Pin: release o=Debian,a=unstable
+Pin: release o=Debian,n=wheezy
 Pin-Priority: 999
 
 Package: console-setup
@@ -236,63 +236,63 @@ Pin: release o=Debian,a=unstable
 Pin-Priority: 999
 
 Package: linux-base
-Pin: release o=Debian,a=unstable
+Pin: release o=Debian,n=wheezy
 Pin-Priority: 999
 
 Package: linux-headers-486
-Pin: release o=Debian,a=unstable
+Pin: release o=Debian,n=wheezy
 Pin-Priority: 999
 
 Package: linux-headers-686-pae
-Pin: release o=Debian,a=unstable
+Pin: release o=Debian,n=wheezy
 Pin-Priority: 999
 
 Package: linux-headers-amd64
-Pin: release o=Debian,a=unstable
+Pin: release o=Debian,n=wheezy
 Pin-Priority: 999
 
 Package: linux-headers-3.2.0-4-common
-Pin: release o=Debian,a=unstable
+Pin: release o=Debian,n=wheezy
 Pin-Priority: 999
 
 Package: linux-headers-3.2.0-4-486
-Pin: release o=Debian,a=unstable
+Pin: release o=Debian,n=wheezy
 Pin-Priority: 999
 
 Package: linux-headers-3.2.0-4-686-pae
-Pin: release o=Debian,a=unstable
+Pin: release o=Debian,n=wheezy
 Pin-Priority: 999
 
 Package: linux-headers-3.2.0-4-amd64
-Pin: release o=Debian,a=unstable
+Pin: release o=Debian,n=wheezy
 Pin-Priority: 999
 
 Package: linux-image-486
-Pin: release o=Debian,a=unstable
+Pin: release o=Debian,n=wheezy
 Pin-Priority: 999
 
 Package: linux-image-686-pae
-Pin: release o=Debian,a=unstable
+Pin: release o=Debian,n=wheezy
 Pin-Priority: 999
 
 Package: linux-image-amd64
-Pin: release o=Debian,a=unstable
+Pin: release o=Debian,n=wheezy
 Pin-Priority: 999
 
 Package: linux-image-3.2.0-4-486
-Pin: release o=Debian,a=unstable
+Pin: release o=Debian,n=wheezy
 Pin-Priority: 999
 
 Package: linux-image-3.2.0-4-686-pae
-Pin: release o=Debian,a=unstable
+Pin: release o=Debian,n=wheezy
 Pin-Priority: 999
 
 Package: linux-image-3.2.0-4-amd64
-Pin: release o=Debian,a=unstable
+Pin: release o=Debian,n=wheezy
 Pin-Priority: 999
 
 Package: linux-kbuild-3.2
-Pin: release o=Debian,a=unstable
+Pin: release o=Debian,n=wheezy
 Pin-Priority: 999
 
 Package: laptop-mode-tools