Use Description-Content-Type instead of pandoc

No need to convert markdown to RST nowadays.

Makefile

@@ -26,5 +26,4 @@ docs: .PHONY
 
 release: .PHONY
 	tox -e py35
-	.tox/py35/bin/pip install pypandoc
 	.tox/py35/bin/python scripts/release

scripts/release

@@ -73,7 +73,6 @@ def push(release_version):
 
 
 def run():
-    environ['USE_PANDOC'] = '1'
     old_version = get_version()
     if not old_version.endswith('.dev0'):
         print("Assuming resumption of interrupted release")

setup.py

@@ -1,22 +1,22 @@
 from setuptools import setup
-import os
 
 
 def get_description():
     return 'A library of composable Python executors'
 
 
 def get_long_description():
-    if os.environ.get('USE_PANDOC') != '1':
-        return
-
-    import pypandoc
-    converted = pypandoc.convert('README.md', 'rst')
+    try:
+        text = open('README.md').read()
+    except IOError as error:
+        if error.errno == 2:
+            return get_description()
+        raise
 
     # The README starts with the same text as "description",
     # which makes sense, but on PyPI causes same text to be
     # displayed twice.  So let's strip that.
-    return converted.replace(get_description() + '.\n\n', '', 1)
+    return text.replace(get_description() + '.\n\n', '', 1)
 
 
 setup(
@@ -29,6 +29,7 @@ def get_long_description():
     license='GNU General Public License',
     description=get_description(),
     long_description=get_long_description(),
+    long_description_content_type='text/markdown',
     classifiers=[
         'Development Status :: 4 - Beta',
         'Intended Audience :: Developers',