remove calls to shelljs from previewprocessor
add meaningful error message
fix recursive cleanup
do directory deletion with rimraf
remove unused imports
Merge branch 'ppshell' of https://github.com/stuartf/Hilary into ppshell
fix code review issues
Follow up on removing shelljs
Merge branch 'ppshell' of https://github.com/stuartf/Hilary into ppshell
Fixed regressions