Add python_requires to setup.py

Author: MilesCranmer

setup.py

@@ -59,8 +59,6 @@ def pyload(path):
 
         # Specify the Python versions you support here. In particular, ensure
         # that you indicate whether you support Python 2, Python 3 or both.
-        'Programming Language :: Python :: 2',
-        'Programming Language :: Python :: 2.7',
         'Programming Language :: Python :: 3',
         'Programming Language :: Python :: 3.4',
         'Programming Language :: Python :: 3.5',
@@ -79,6 +77,7 @@ def pyload(path):
       packages=find_packages("src"),
       package_dir={"": "src"},
       package_data={"julia": ["*.jl"]},
+      python_requires=">=3.4",
       extras_require={
           # Update `ci/test-upload/tox.ini` when "test" is changed:
           "test": [