Cleanup py27 support

Make a few cleanups:
- Remove python 2.7 stanza from setup.py
- Add requires on python >= 3.6 to setup.cfg so that pypi and pip
  know about the requirement
- Update classifiers
- Update requirements, no need for python_version anymore

Change-Id: I051224a8a943bc0fe83cc507538d888aeff5af8d

setup.cfg

@@ -3,8 +3,11 @@ name = blazar-nova
 summary = Nova related filters and extensions for Blazar
 description-file = README.rst
 license = Apache Software License
+python-requires = >=3.6
 classifiers =
     Programming Language :: Python
+    Programming Language :: Python :: Implementation :: CPython
+    Programming Language :: Python :: 3 :: Only
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7

setup.py

@@ -13,17 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# THIS FILE IS MANAGED BY THE GLOBAL REQUIREMENTS REPO - DO NOT EDIT
 import setuptools
 
-# In python < 2.7.4, a lazy loading of package `pbr` will break
-# setuptools if some other modules registered functions in `atexit`.
-# solution from: http://bugs.python.org/issue15881#msg170215
-try:
-    import multiprocessing  # noqa
-except ImportError:
-    pass
-
 setuptools.setup(
     setup_requires=['pbr>=2.0.0'],
     pbr=True)

test-requirements.txt

@@ -6,7 +6,7 @@ hacking!=0.13.0,<0.14,>=0.12.0 # Apache-2.0
 
 nose>=1.3.7 # LGPL
 mock>=2.0.0 # BSD
-sphinx!=1.6.6,!=1.6.7,>=1.6.2;python_version>='3.4' # BSD
+sphinx!=1.6.6,!=1.6.7,>=1.6.2 # BSD
 sphinxcontrib-httpdomain>=1.3.0 # BSD
 
 fixtures>=3.0.0 # Apache-2.0/BSD