Prevent installation on Python 2 (Fixes #244)

CHANGELOG.md

@@ -8,6 +8,7 @@ The format mostly follows [Keep a Changelog](http://keepachangelog.com/en/1.0.0/
 
 ### Changed
 - Moved ChangeLog file to CHANGELOG.md and using Keep a Changelog format.
+- Force version check in `setup.py`, to exclude Python 2 (Fixes #244)
 
 ### Removed
 - Old ChangeLog entries

setup.py

@@ -4,18 +4,23 @@
 
 import os
 import re
+import sys
 
 main_py = open(os.path.join('lib', 'urlwatch', '__init__.py')).read()
 m = dict(re.findall("\n__([a-z]+)__ = '([^']+)'", main_py))
 docs = re.findall('"""(.*?)"""', main_py, re.DOTALL)
 
+if sys.version_info < (3, 3):
+    sys.exit('urlwatch requires Python 3.3 or newer')
+
 m['name'] = 'urlwatch'
 m['author'], m['author_email'] = re.match(r'(.*) <(.*)>', m['author']).groups()
 m['description'], m['long_description'] = docs[0].strip().split('\n\n', 1)
 m['install_requires'] = ['minidb', 'PyYAML', 'requests', 'keyring', 'pycodestyle', 'appdirs']
 m['scripts'] = ['urlwatch']
 m['package_dir'] = {'': 'lib'}
 m['packages'] = ['urlwatch']
+m['python_requires'] = '>3.3.0'
 m['data_files'] = [
     ('share/man/man1', ['share/man/man1/urlwatch.1']),
     ('share/urlwatch/examples', [