Update version and changelog for v1.5.2
diff --git a/CHANGELOG b/CHANGELOG
index 16ef00f..c31790c 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,14 @@
+v1.5.2
+ Version 1.5.2
+
+ Bugfix release
+
+ - Allow using oauth2client >= 1.5.0, < 4.0.0. (#265)
+ - Fix project_id argument description. (#257)
+ - Retry chunk uploaded on rate limit exceeded errors. (#255)
+ - Obtain access token if necessary in BatchHttpRequest.execute(). (#232)
+ - Warn when running tests using HttpMock without having a cache. (#261)
+
v1.5.1
Version 1.5.1