add msgpack-python as a library dependency

Author: Emanuele Palazzetti

setup.py

@@ -58,6 +58,7 @@ def run_tests(self):
     packages=find_packages(exclude=['tests*']),
     install_requires=[
         "wrapt",
+        "msgpack-python",
     ],
     # plugin tox
     tests_require=['tox', 'flake8'],