tv_node() wasn't properly escaping strings for JSON
tv_node() wasn't properly escaping strings for JSON

This fixes #96

htem/CATMAID,htem/CATMAID,fzadow/CATMAID,fzadow/CATMAID,htem/CATMAID,fzadow/CATMAID,htem/CATMAID,fzadow/CATMAID