Adding grpcio to setup.py.

grpcio can only be installed with Python 2.7, so the
py27 tox environment is the only one that doesn't need to
run without mocks.

Author: dhermes

setup.py

@@ -1,5 +1,5 @@
 import os
-
+import sys
 
 from setuptools import setup
 from setuptools import find_packages
@@ -19,6 +19,8 @@
     'pyOpenSSL',
     'six',
 ]
+if sys.version_info[:2] == (2, 7):
+    REQUIREMENTS.append('grpcio >= 0.13.0')
 
 setup(
     name='gcloud',

tox.ini

@@ -21,6 +21,12 @@ covercmd =
       --cover-branches \
       --nocapture
 
+[testenv:py27]
+basepython =
+    python2.7
+setenv =
+    PYTHONPATH =
+
 [testenv:cover]
 basepython =
     python2.7