Switch to using markdown for package documentation

* Remove the markdown to rst conversion from setup.py.

setup.py

@@ -2,20 +2,9 @@
 import os
 import re
 from setuptools import setup
-from m2r import parse_from_file
-import restructuredtext_lint
 
-# Parser README.md into reStructuredText format
-rst_readme = parse_from_file('README.md')
-
-# Validate the README, checking for errors
-errors = restructuredtext_lint.lint(rst_readme)
-
-# Raise an exception for any errors found
-if errors:
-    print(rst_readme)
-    raise ValueError('README.md contains errors: ',
-                     ', '.join([e.message for e in errors]))
+with open('README.md', 'r') as f:
+    readme_md = '\n'.join(f.readlines())
 
 # Attempt to get version number from TravisCI environment variable
 version = os.environ.get('TRAVIS_TAG', default='0.0.0')
@@ -26,7 +15,8 @@ version = re.sub('^v', '', version)
 setup(
     name='anybadge',
     description='Simple, flexible badge generator for project badges.',
-    long_description=rst_readme,
+    long_description=readme_md,
+    long_description_content_type='text/markdown',
     version=version,
     author='Jon Grace-Cox',
     author_email='jongracecox@gmail.com',