Added sing wrapper for squid test

SiteTests/FroNtier/tests/CE-cms-squid.sing

+#!/bin/bash
+
+TEST_SCRIPT=`basename $0 | sed 's/\.sing//'`
+echo "Will run $TEST_SCRIPT with Singularity if available"
+source ${SAME_SENSOR_HOME}/tests/CE-cms-singularity-wrapper ${TEST_SCRIPT}