Cleanup py27 support

Make a few cleanups:
- Remove python 2.7 stanza from setup.py
- Remove obsolete sections from setup.cfg
- Remove install_command from tox.ini, the default is fine

Change-Id: I693afdb7097b156935424c5549e1b22a08bf2773

setup.cfg

@@ -10,6 +10,3 @@ classifier =
     Intended Audience :: Developers
     License :: OSI Approved :: Apache Software License
     Operating System :: POSIX :: Linux
-
-[wheel]
-universal = 1

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'],
     pbr=True)

tox.ini

@@ -6,7 +6,6 @@ skipsdist = True
 basepython = python3
 usedevelop = True
 setenv = VIRTUAL_ENV={envdir}
-install_command = pip install -U {opts} {packages}
 deps = -r{toxinidir}/doc/requirements.txt
 whitelist_externals =
   find