Cleanup setup.py and requirements

- Python 2 is no longer supported
- setup.py is no longer managed by the global tooling
- Recent pip does not require appropriate order in requirement files

Change-Id: I8853a4221c6da78f860e821be4a063176c5734f3

requirements.txt

@@ -1,7 +1,3 @@
-# The order of packages is significant, because pip processes them in the order
-# of appearance. Changing the order has an impact on the overall integration
-# process, which may cause wedges in the gate later.
-
 # See: https://bugs.launchpad.net/pbr/+bug/1384919 for why this is here...
 pbr!=2.1.0,>=2.0.0 # Apache-2.0
 

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)