Add CHANGES to setup.py long_description

This adds the CHANGES to the long_description so it shows up in PyPI
on the package page. This surfaces warnings for backwards-incompatible
changes there where users might be looking.

Fixes #180

Author: willkg

README.rst

@@ -101,3 +101,5 @@ The simplest way to use Bleach is:
 .. _GitHub: https://github.com/mozilla/bleach
 .. _ReadTheDocs: http://bleach.readthedocs.org/
 .. _PyPI: http://pypi.python.org/pypi/bleach
+
+

setup.py

@@ -14,11 +14,18 @@
     # https://github.com/html5lib/html5lib-python/pull/177)
     install_requires.append('ordereddict')
 
+
+def get_long_desc():
+    desc = open('README.rst').read()
+    desc += open('CHANGES').read()
+    return desc
+
+
 setup(
     name='bleach',
     version='1.4.2',
     description='An easy whitelist-based HTML-sanitizing tool.',
-    long_description=open('README.rst').read(),
+    long_description=get_long_desc(),
     maintainer='Jannis Leidel, Will Kahn-Greene',
     url='http://github.com/mozilla/bleach',
     license='Apache Software License',