[devtools/qunit] Turn FirefoxHelper into a context manager So that stop() method always gets called. Also ensure temporary directory created on __init__ gets deleted as well upon exit.

#! /bin/sh -e
 
case "$1" in
    remove)
	if [ -x "/etc/init.d/cubicweb-ctl" ]; then
	    invoke-rc.d cubicweb-ctl stop || true
	fi
    ;;
esac
 
#DEBHELPER#
 
exit 0