Fix generated packages

Besides cinderlib and cinderlib.persistence we were also including a
"tests" package we shouldn't be including.

This patch corrects this by fixing the exclude pattern in the
`setuptools.find_packages` call.

setup.py

@@ -56,7 +56,7 @@ setuptools.setup(
     author="Gorka Eguileor",
     author_email='geguileo@redhat.com',
     url='https://github.com/akrog/cinderlib',
-    packages=setuptools.find_packages(exclude=['tmp', 'tests.*', 'tests.*']),
+    packages=setuptools.find_packages(exclude=['tmp', 'tests*']),
     include_package_data=True,
     install_requires=requirements,
     extras_requires=extras,