Testing on backend API calls, using mock; add runtests.py.

Cherry-picked from:
8c26807a - Add runtests.py for testing separately from other Django apps
cd8504b1 - Make tests compatible with setuptools
4ac65b78 - Set up testing on the backend API calls, using mock

setup.py

@@ -14,6 +14,8 @@ setup(
     zip_safe=False,
     install_requires=["requests", "django"],
     include_package_data=True,
+    test_suite="runtests.runtests",
+    test_requires=["mock"],
     classifiers=[
         "Programming Language :: Python",
         "Topic :: Software Development :: Libraries :: Python Modules",