Update names of README and CHANGELOG

Author: pdp7

setup.py

@@ -44,7 +44,7 @@
       author           = 'Justin Cooper',
       author_email     = 'justin@adafruit.com',
       description      = 'A module to control BeagleBone IO channels',
-      long_description = open_as_utf8('README.rst').read() + open_as_utf8('CHANGELOG.rst').read(),
+      long_description = open_as_utf8('README.md').read() + open_as_utf8('CHANGELOG.md').read(),
       license          = 'MIT',
       keywords         = 'Adafruit BeagleBone IO GPIO PWM ADC',
       url              = 'https://github.com/adafruit/adafruit-beaglebone-io-python/',