update setup to remove need to build theme, clean up readme, bump pyyaml dep (#555)

site/_utils/setup.sh

@@ -1,11 +0,0 @@
-#! /bin/bash
-
-if pwd | egrep -q '\s'; then
-	echo "Working directory name contains one or more spaces."
-	exit 1
-fi
-
-which python3 || { echo "Failed to find python3. Try installing Python for your operative system: https://www.python.org/downloads/" && exit 1; }
-which poetry || curl -sSL https://install.python-poetry.org | python3 -
-
-poetry install