Use RST type for long description (#61)

setup.py

@@ -71,7 +71,7 @@ def __init__(self, *args, **kwargs):
     author="Blue Brain Project, EPFL",
     description="Simulation and Neural network Analysis Productivity layer",
     long_description=README,
-    long_description_content_type='text/markdown',
+    long_description_content_type='text/x-rst',
     license="LGPLv3",
     url='https://github.com/BlueBrain/snap',
     keywords=[