Misc edits to disable jobs hung on unresponsive nodes.

jjb/voltha-test/voltha-certification.yaml
jjb/voltha-test/voltha-certification/voltha-2.11.yaml
jjb/voltha-test/voltha-certification/voltha-2.12.yaml
jjb/voltha-test/voltha-certification/voltha-2.8.yaml
-----------------------------------------------------
  o Disable more menlo-certification jobs since cluster is offline.
  o Refactor altered 1600g jobs into configs named for branch/release.

requirements.txt
----------------
  o Added versioned urllib3 module so sphinx + python v3.6 will not barf.

Makefile
makefiles/lint/include.mk
makefiles/lint/doc8/include.mk
------------------------------
  o More updates from repo:onf-make, added library target lint-doc8.

makefiles/jjb/targets.mk
------------------------
  o build target - added a dependency on activate script so virtualenv
    will install on demand.  Worked by coincidence earlier, make lint
    also depends on venv.

jjb/voltha-e2e.yaml
-------------------
  o Purge lingering comments from joba-into-versioned-configs refactoring.
  o No fallout reported when configs were changed earlier.

Change-Id: I2571feb883a2049feb0781fc2464b875e3af325e
diff --git a/Makefile b/Makefile
index e1e394f..30ca940 100644
--- a/Makefile
+++ b/Makefile
@@ -60,6 +60,7 @@
 	@echo 'Usage: $(MAKE) help ...'
 	@echo '  % make clean sterile'
 	@echo '  % make lint lint-jjb'
+	@echo '  % make build           # jjb-gen'
 	@echo '  % make test'
 	@echo '  % make help            # show all available targes'