Merge pull request #380 from zezha-msft/fix-requirements-python-3.3

Require cryptography <= 1.9 for python 3.3

requirements.txt

@@ -3,4 +3,5 @@ python-dateutil
 requests>=2.9.2
 vcrpy
 azure-common
-cryptography>=1.3.0
+cryptography>=1.3.0;python_version!="3.3"
+cryptography<=1.9.0;python_version=="3.3"