Declare namespace packages in setup.py

----Release Notes----
[]
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=119856939

Author: silviulica

setup.py

@@ -102,6 +102,7 @@ def get_download_url():
     download_url=get_download_url(),
     author='Google, Inc.',
     packages=setuptools.find_packages(),
+    namespace_packages=['google', 'google.cloud'],
     entry_points={
         'console_scripts': CONSOLE_SCRIPTS,
         },