Update changelog for 0.12.1 release.

debian/changelog

+tails (0.12.1) unstable; urgency=low
+
+This is a brown paper bag release to fix two major problems introduced in
+Tails 0.12.
+
+  * Iceweasel
+  - Upgrade Torbutton to 1.4.6.
+  - Upgrade AdBlock Plus to 2.1.
+  - Update AdBlock Plus patterns.
+
+  * Hardware support
+  - Upgrade Linux to 3.2.21-3 (linux-image-3.2.0-3-486).
+
+  * Software
+  - Install MAT from Debian backports, drop custom package.
+  - Install python-pdfrw to re-add PDF support to the MAT.
+  - Upgrade tails-greeter to 0.7.1, which fixes the race condition that
+    broke administration password and locale settings on some systems.
+
+  * Boot
+  - Remove the Tails specific plymouth theme. The theme interfers heavily with
+    the boot process on some hardware.
+
+ -- Tails developers <amnesia@boum.org>  Thu, 28 Jun 2012 13:37:00 +0200
+
 tails (0.12) unstable; urgency=low
 
   * Major new features