setup.py: added classifiers

https://pypi.org/classifiers/

setup.py

@@ -16,8 +16,15 @@ setuptools.setup(
         'subfields',
     ],
     classifiers=[
-        # TODO add classifiers
-        'Programming Language :: Python',
+        'Development Status :: 3 - Alpha',
+        'Intended Audience :: Healthcare Industry',
+        'Intended Audience :: Science/Research',
+        'Programming Language :: Python :: 3.5',
+        'Programming Language :: Python :: 3.6',
+        'Programming Language :: Python :: 3.7',
+        'Topic :: Scientific/Engineering :: Information Analysis',
+        'Topic :: Scientific/Engineering :: Medical Science Apps.',
+        'Topic :: Utilities',
     ],
     packages=setuptools.find_packages(),
     entry_points={