Update setup.py

Author: Michael Davis

setup.py

@@ -43,7 +43,14 @@ def get_packages(package):
         'Topic :: Utilities',
     ],
     install_requires=[
-        'pycrypto==2.6.1',
-        'six==1.9.0',
+        'pycrypto >=2.6.0 <2.7.0',
+        'six >=1.9.0 <1.10.0',
+    ],
+    test_requires=[
+        'pycrypto >=2.6.0 <2.7.0',
+        'six >=1.9.0 <1.10.0',
+        'pytest >=2.7.0'
+        'pytest-cov >=1.8.0'
     ]
+
 )