Merge pull request #40 from Axelrod-Python/version

Alter python requirement to >=3.5

Author: marcharper

setup.py

@@ -56,5 +56,5 @@ def read(*names, **kwargs):
     install_requires=[
         'axelrod == 3.1.2',
     ],
-    python_requires=">=3.6",
+    python_requires=">=3.5",
 )