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
 
diff --git a/googleapiclient/__init__.py b/googleapiclient/__init__.py
index b911ff0..0753586 100644
--- a/googleapiclient/__init__.py
+++ b/googleapiclient/__init__.py
@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-__version__ = "1.5.2"
+__version__ = "1.5.3"
 
 # Set default logging handler to avoid "No handler found" warnings.
 import logging