Updating author_email in all setup.py. (#3598)

Done via:

$ git grep -l author_email | \
> xargs sed -i s/jjg+google-cloud-python@google.com/googleapis-publisher@google.com/g

and manually editing `videointelligence/setup.py` and `vision/setup.py`.

Author: dhermes

packages/google-cloud-datastore/setup.py

@@ -27,7 +27,7 @@
 #       consolidate.
 SETUP_BASE = {
     'author': 'Google Cloud Platform',
-    'author_email': 'jjg+google-cloud-python@google.com',
+    'author_email': 'googleapis-publisher@google.com',
     'scripts': [],
     'url': 'https://github.com/GoogleCloudPlatform/google-cloud-python',
     'license': 'Apache 2.0',