Fix the setup, remove tests

setup.py

@@ -11,8 +11,7 @@ setup(
     url = 'https://github.com/emesik/monero-python/',
     long_description = open('README.rst').read(),
     install_requires = open('requirements.txt', 'r').read().splitlines(),
-    packages = find_packages(),
-    data_files = ['requirements.txt'],
+    packages = find_packages('.', exclude=['tests']),
     include_package_data = True,
     author = 'Michał Sałaban',
     author_email = 'michal@salaban.info',