added a `python setup.py test` directive that invokes pytest

setup.cfg

@@ -10,3 +10,6 @@ exclude=
 # ignore spaces around keyword arguments and dict entries,
 # which are very useful for alignment
 ignore=E221,E251,E241,E501
+
+[aliases]
+test=pytest

setup.py

@@ -3,7 +3,8 @@ from setuptools import find_packages, setup
 setup(
     name='mozilla-taar',
     use_scm_version=True,
-    setup_requires=['setuptools_scm'],
+    setup_requires=['setuptools_scm', 'pytest-runner'],
+    tests_require=['pytest'],
     include_package_data = True,
     packages=find_packages(exclude=['tests', 'tests/*']),
     description='Telemetry-Aware Addon Recommender',