Drop python 2.7 support and testing

OpenStack is dropping the py2.7 support in ussuri cycle.

compute-hyperv is ready with python 3 and ok to drop the
python 2.7 support.

Complete discussion & schedule can be found in
- http://lists.openstack.org/pipermail/openstack-discuss/2019-October/010142.html
- https://etherpad.openstack.org/p/drop-python2-support

Ussuri Communtiy-wide goal - https://review.opendev.org/#/c/691178/

Change-Id: I58d4843f05703b62db94220965980612f803fd9e

releasenotes/notes/drop-py-2-7-5cd36052d5c2e594.yaml

@@ -0,0 +1,6 @@
+---
+upgrade:
+  - |
+    Python 2.7 support has been dropped. Last release of compute-hyperv
+    to support py2.7 is OpenStack Train. The minimum version of Python now
+    supported by compute-hyperv is Python 3.6.

setup.cfg

@@ -15,8 +15,6 @@ classifier =
     License :: OSI Approved :: Apache Software License
     Operating System :: Microsoft :: Windows
     Programming Language :: Python
-    Programming Language :: Python :: 2
-    Programming Language :: Python :: 2.7
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3.5
     Programming Language :: Python :: 3.6

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 minversion = 2.0
-envlist = py27,py35,py36,pep8,pip-missing-reqs
+envlist = py35,py36,pep8,pip-missing-reqs
 skipsdist = True
 
 [testenv]