Update changelog for 1.5.1.

debian/changelog

-tails (1.6) UNRELEASED; urgency=medium
+tails (1.5.1) unstable; urgency=medium
 
-  * Dummy entry for next minor release.
+  * Security fixes
+    - Upgrade Tor Browser to 5.0.2. (Closes: #10112)
+    - Upgrade gdk-pixbuf packages to 2.26.1-1+deb7u1.
+    - Upgrade libnss3 to 2:3.14.5-1+deb7u5.
+
+  * Bugfixes
+    - Refresh Tor Browser AppArmor profile patch. The old one doesn't
+      apply on top of testing's torbrowser-launcher anymore.
+
+  * Build system
+    - Make sure Jenkins creates new jobs to build the testing branch
+      after freezes. (Closes: #9925)
 
- -- Tails developers <tails@boum.org>  Tue, 11 Aug 2015 19:30:00 +0200
+ -- Tails developers <tails@boum.org>  Fri, 28 Aug 2015 01:52:14 +0200
 
 tails (1.5) unstable; urgency=medium