Renamed README.

Author: Lance Edgar

README.txt renamed to README.rst

@@ -30,7 +30,7 @@
 here = os.path.abspath(os.path.dirname(__file__))
 execfile(os.path.join(here, 'sqlalchemy_pervasive', '_version.py'))
 
-README = open(os.path.join(here, 'README.txt')).read()
+README = open(os.path.join(here, 'README.rst')).read()
 CHANGES = open(os.path.join(here, 'CHANGES.rst')).read()