Add Python 3 package targets

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

setup.cfg

@@ -1,2 +1,5 @@
+[bdist_wheel]
+universal = 1
+
 [wheel]
-python-tag = py2
+python-tag = py2.py3

setup.py.tmpl

@@ -79,6 +79,11 @@ setup(
         'Natural Language :: English',
         'Programming Language :: Python',
         'Programming Language :: Python :: 2.7',
+        'Programming Language :: Python :: 3',
+        'Programming Language :: Python :: 3.4',
+        'Programming Language :: Python :: 3.5',
+        'Programming Language :: Python :: 3.6',
+        'Programming Language :: Python :: 3.7',
         'Topic :: Internet :: WWW/HTTP',
         'Topic :: Internet :: WWW/HTTP :: WSGI :: Application',
         'Topic :: Communications :: File Sharing',
@@ -91,6 +96,7 @@ setup(
     name=PACKAGE_NAME,
     packages=find_packages(PACKAGE_DIR),
     platforms=['any'],
+    python_requires = '>=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*',
     scripts=['mayan/bin/mayan-edms.py'],
     url='https://gitlab.com/mayan-edms/mayan-edms',
     version=mayan.__version__,