Use python_requires and raise an error if an older Python is used

setup.py

@@ -1,14 +1,15 @@
 # -*- coding:utf-8 -*-
 
 import os
+import sys
 from setuptools import setup, find_packages
 
+if sys.version_info[:2] < (3, 5):
+    sys.exit('Sigal supports Python 3.5+ only')
+
 with open('README.rst') as f:
     README = f.read()
 
-with open('docs/changelog.rst') as f:
-    CHANGELOG = f.read()
-
 # Load package meta from the pkgmeta module without loading the package.
 pkgmeta = {}
 pkgmeta_file = os.path.join(os.path.dirname(__file__), 'sigal', 'pkgmeta.py')
@@ -24,11 +25,12 @@ setup(
     author=pkgmeta['__author__'],
     author_email='contact@saimon.org',
     description='Simple static gallery generator',
-    long_description=README + '\n' + CHANGELOG,
+    long_description=README,
     packages=find_packages(exclude=['tests*']),
     zip_safe=False,
     include_package_data=True,
     platforms='any',
+    python_requires='>=3.5',
     keywords=['gallery', 'static', 'generator', 'image', 'video', 'galleria'],
     install_requires=['blinker', 'click', 'Jinja2', 'Markdown',
                       'Pillow>=4.0.0', 'pilkit'],
@@ -44,10 +46,7 @@ setup(
         'Environment :: Console',
         'License :: OSI Approved :: MIT License',
         'Operating System :: OS Independent',
-        'Programming Language :: Python :: 2',
-        'Programming Language :: Python :: 2.7',
         'Programming Language :: Python :: 3',
-        'Programming Language :: Python :: 3.4',
         'Programming Language :: Python :: 3.5',
         'Programming Language :: Python :: 3.6',
         'Topic :: Internet :: WWW/HTTP',

sigal/__init__.py

@@ -40,6 +40,9 @@ from .utils import copy
 
 _DEFAULT_CONFIG_FILE = 'sigal.conf.py'
 
+if sys.version_info[:2] < (3, 5):
+    raise Exception('Sigal supports Python 3.5+ only')
+
 
 @click.group()
 @click.version_option(version=__version__)