fill in license metadata in setuptools

setup.py

@@ -9,12 +9,15 @@
     maintainer_email='[email protected]',
     packages=['pydrive', 'pydrive.test'],
     url='https://github.com/googleworkspace/PyDrive',
-    license='LICENSE',
+    license='Apache 2.0',
     description='Google Drive API made easy.',
     long_description=open('README.rst').read(),
     install_requires=[
         "google-api-python-client >= 1.2",
         "oauth2client >= 4.0.0",
         "PyYAML >= 3.0",
     ],
+    classifiers=[
+        'License :: OSI Approved :: Apache Software License',
+    ],
 )