docs(CHANGELOG): add 1.2.31 release info

Author: petebacondarwin

CHANGELOG.md

@@ -1,3 +1,25 @@
+<a name="1.4.13"></a>
+# 1.4.13 croaking-elderweed (2016-10-10)
+
+## Bug Fixes
+- **input:** ensure that hidden input values are correct after history back
+  ([693d1334](https://github.com/angular/angular.js/commit/693d1334566f78987f5a361a100db4f889f35abd)
+
+
+<a name="1.2.31"></a>
+# 1.2.31 barking-moustache (2016-10-10)
+
+## Bug Fixes
+- **input:** ensure that hidden input values are correct after history back
+  ([7ec663fc](https://github.com/angular/angular.js/commit/7ec663fc708aa7a9a9ce62d2306f24d7a733a86d)
+
+
+<a name="1.4.12"></a>
+# 1.4.12
+
+*Invalid release*
+
+
 <a name="1.5.8"></a>
 # 1.5.8 arbitrary-fallbacks (2016-07-22)