Update setup.py

File "setup.py", line 9, in <module>
    with open(os.path.join(here, 'README')) as f:
IOError: [Errno 2] No such file or directory:++++

Author: SartoNess

setup.py

@@ -6,7 +6,7 @@
 from bitcoin import __version__
 
 here = os.path.abspath(os.path.dirname(__file__))
-with open(os.path.join(here, 'README')) as f:
+with open(os.path.join(here, 'README.md')) as f:
     README = f.read()
 
 requires = []