Fix long_description and add manifest.

MANIFEST.in

@@ -0,0 +1,2 @@
+include LICENSE
+include README.md

setup.py

@@ -1,16 +1,19 @@
 from setuptools import setup
 
+with open('README.md') as readme_file:
+    long_description = readme_file.read()
+
 setup(
     name='rgkit',
-    version='0.3.5',
+    version='0.3.6',
     description='Robot Game Testing Kit',
     maintainer='Peter Wen',
     maintainer_email='[email protected]',
     url='https://github.com/WhiteHalmos/rgkit',
     packages=['rgkit', 'rgkit.render'],
     package_data={'rgkit': ['bots/*.py', 'maps/*.py']},
     license='Unlicense',
-    long_description=open('README.md', 'r').read(),
+    long_description=long_description,
     entry_points={
         'console_scripts': [
             'rgrun = rgkit.run:main',