update version datestamp for June 2013 release

git-svn-id: http://google-cache-invalidation-api.googlecode.com/svn/trunk/src/google@307 1cc9d426-c294-39be-ba72-c0199ca0f247
diff --git a/cacheinvalidation/impl/build_constants.h b/cacheinvalidation/impl/build_constants.h
index 5cb9fc9..f4c44c6 100644
--- a/cacheinvalidation/impl/build_constants.h
+++ b/cacheinvalidation/impl/build_constants.h
@@ -17,6 +17,6 @@
 #ifndef INVALIDATION_BUILD_CONSTANTS_H_
 #define INVALIDATION_BUILD_CONSTANTS_H_
 namespace invalidation {
-const int BUILD_DATESTAMP = 20130429;
+const int BUILD_DATESTAMP = 20130604;
 }  // namespace invalidation
 #endif  // INVALIDATION_BUILD_CONSTANTS_H_