Change build to use python 3, minor lint fixes

Change-Id: I3a07c58efb8b676f77426a6ff8cb3e40f13d3f1f
diff --git a/Makefile b/Makefile
index 4d57f91..724d01c 100644
--- a/Makefile
+++ b/Makefile
@@ -19,7 +19,7 @@
 
 # Create the virtualenv with all the tools installed
 doc_venv:
-	virtualenv doc_venv ;\
+	virtualenv -p python3 doc_venv ;\
 	source ./doc_venv/bin/activate ;\
 	pip install livereload ;\
 	pip install -r requirements.txt