Problem: Python version not check before running (#2179)

Solution: Check python version

setup.py

@@ -5,8 +5,12 @@
 
 """
 from setuptools import setup, find_packages
+import sys
 
 
+if sys.version_info < (3, 6):
+    sys.exit('Please use python version 3.6 or higher')
+
 # get the version
 version = {}
 with open('bigchaindb/version.py') as fp:
@@ -107,7 +111,7 @@ def check_setuptools_features():
     author_email='dev@bigchaindb.com',
     license='Apache Software License 2.0',
     zip_safe=False,
-
+    python_requires='>=3.6',
     classifiers=[
         'Development Status :: 3 - Alpha',
         'Intended Audience :: Developers',