Fix setup.py for Python 3.5, include PyTorch

setup.py

@@ -2,20 +2,29 @@
 # -*- coding: utf-8 -*-
 
 from setuptools import setup, find_packages
+import sys
+
+valid_python = sys.version_info[0] >= 3 and sys.version_info[1] >= 5
+if not valid_python:
+    raise RuntimeError("gptorch requires python 3.5+")
+
+# Python 3.5 can't do matplotlib 3.1 and up.
+matplotlib_dependency = "matplotlib>=2.1.2" if sys.version_info[1] >= 6 else \
+    "matplotlib>=2.1.2, <3.1"
 
 requirements = [
     "numpy>=1.10",
     "scipy>=0.18",
-    "matplotlib>=2.1.2",
+    matplotlib_dependency,
     "scikit-learn>=0.19.1",
-    # "pytorch",  # conda install pytorch -c pytorch
+    "torch",  # conda install pytorch -c pytorch
     "pytest>=3.5.0",
     "graphviz>=0.9",
     "jupyter"
 ]
 
 setup(name="gptorch",
-    version="0.2.0",
+    version="0.2.1",
     description="gptorch - a Gaussian process toolbox built on PyTorch",
     author="Yinhao Zhu, Steven Atkinson",
     author_email="[email protected], [email protected]",