Adding back .dev1 suffix after #4644. (#4651)

Also adding a newly added note to Pub / Sub release notes
(I already added this in the official release).

Author: dhermes

setup.py

@@ -68,7 +68,7 @@
 
 setup(
     name='google-api-core',
-    version='0.1.3',
+    version='0.1.4.dev1',
     description='Core Google API Client Library',
     long_description=README,
     namespace_packages=['google'],