Standardize Armada code with YAPF

From recently merged document updates in [0] there is a desire to
standardize the Airship project python codebase.  This is the effort
to do so for the Armada project.

[0] https://review.opendev.org/#/c/671291/

Change-Id: I4fe916d6e330618ea3a1fccfa4bdfdfabb9ffcb2

tox.ini

@@ -72,7 +72,7 @@ commands =
     # Whitespace linter (for chart files)
     bash {toxinidir}/tools/whitespace-linter.sh
     yapf -dr {toxinidir}/armada {toxinidir}/setup.py
-    flake8 {posargs}
+    flake8 {toxinidir}/armada {toxinidir}/setup.py
     # Run security linter as part of the pep8 gate instead of a separate zuul job.
     bandit -r armada -n 5 -x armada/tests/*
 
@@ -94,7 +94,7 @@ commands =
     coverage xml -o cover/coverage.xml
     coverage report
 
-[testenv:yapf]
+[testenv:fmt]
 basepython = python3
 deps = {[testenv]deps}
 commands =
@@ -102,8 +102,14 @@ commands =
 
 [flake8]
 filename = *.py
-# These are ignored intentionally:
-# W504 - line break after binary operator, we cannot have both
-#        W503 and W504 enabled
-ignore = W504
+show-source = true
+# [H106] Don't put vim configuration in source files.
+# [H201] No 'except:' at least use 'except Exception:'
+# [H904] Delay string interpolations at logging calls.
+enable-extensions = H106,H201,H904
+# [W503] line break before binary operator
+ignore = W503
 exclude = .git,.tox,dist,*lib/python*,*egg,build,releasenotes,doc/*,hapi,venv
+max-complexity = 24
+application-import-names = armada
+import-order-style = pep8