Update version and changelog for v1.5.3
diff --git a/CHANGELOG b/CHANGELOG
index c31790c..f2462be 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,10 @@
+v1.5.3
+  Version 1.5.3
+
+  Bugfix release
+
+  - Fixed import error with oauth2client >= 3.0.0. (#270)
+
 v1.5.2
   Version 1.5.2