Update dependencies

requirements.txt

-requests>=2.4.3
-requests_oauthlib>=0.4.1
-six>=1.7.3
+requests>=2.11.1
+requests_oauthlib>=0.7.0
+six>=1.10.0

test_requirements.txt

 tox>=1.7.2
-vcrpy==1.1.2
+vcrpy==1.10.3
 mock==1.0.1
 unittest2   # Comment this line out if using Python 3.