Update changelog for 1.2.2.

debian/changelog

-tails (1.2.2) UNRELEASED; urgency=medium
+tails (1.2.2) unstable; urgency=medium
 
-  * Dummy changelog entry for the next point release.
+  * Bugfixes
+    - Create a CA bundle for Tails Upgrader at ISO build time, and
+      patch tails-iuk to use it. Specifically this will make it
+      possible to check for Tails upgrades after our website changes
+      certificate around the 2014 to 2015 transition (Partially fixes
+      #8404).
 
- -- Tails developers <amnesia@boum.org>  Wed, 03 Dec 2014 18:30:37 +0100
+ -- Tails developers <tails@boum.org>  Mon, 15 Dec 2014 10:05:17 +0100
 
 tails (1.2.1) unstable; urgency=low