Cleanup py27 support

This repo is now testing only with Python 3, so let's make
a few cleanups:
- Remove python 2.7 stanza from setup.py
- Remove obsolete sections from setup.cfg
- Update classifiers
- Remove install_command from tox.ini, the default is fine
- Remove babel.cfg, it's not needed anymore.
- Use TOX_CONSTRAINTS_FILE, UPPER_CONSTRAINTS_FILE is obsolete

Change-Id: I235cf10f6a619fa6c41e688a17337385a1034aa2

babel.cfg

@@ -1,2 +0,0 @@
-[python: **.py]
-

setup.cfg

@@ -14,6 +14,8 @@ classifier =
     License :: OSI Approved :: Apache Software License
     Operating System :: POSIX :: Linux
     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
@@ -21,34 +23,3 @@ classifier =
 [files]
 packages =
     devstack
-
-[build_sphinx]
-source-dir = doc/source
-build-dir = doc/build
-all_files = 1
-
-[upload_sphinx]
-upload-dir = doc/build/html
-
-[entry_points]
-console_scripts =
-    dsconf = devstack.cmd:main
-
-[compile_catalog]
-directory = devstack/locale
-domain = devstack
-
-[update_catalog]
-domain = devstack
-output_dir = devstack/locale
-input_file = devstack/locale/devstack.pot
-
-[extract_messages]
-keywords = _ gettext ngettext l_ lazy_gettext
-mapping_file = babel.cfg
-output_file = devstack/locale/devstack.pot
-
-[build_releasenotes]
-all_files = 1
-build-dir = releasenotes/build
-source-dir = releasenotes/source

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>=1.8'],
     pbr=True)

tox.ini

@@ -7,11 +7,12 @@ ignore_basepython_conflict = True
 [testenv]
 basepython = python3
 usedevelop = True
-install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} {opts} {packages}
 setenv =
    VIRTUAL_ENV={envdir}
    PYTHONWARNINGS=default::DeprecationWarning
-deps = -r{toxinidir}/test-requirements.txt
+deps =
+   -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+   -r{toxinidir}/test-requirements.txt
 commands = python setup.py test --slowest --testr-args='{posargs}'
 
 [testenv:pep8]
@@ -25,7 +26,7 @@ commands = python setup.py test --coverage --testr-args='{posargs}'
 
 [testenv:docs]
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r{toxinidir}/requirements.txt
   -r{toxinidir}/doc/requirements.txt
 commands =
@@ -34,6 +35,7 @@ commands =
 whitelist_externals = rm
 
 [testenv:releasenotes]
+deps = {[testenv:docs]deps}
 commands =
   sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html