Check for presence of custom.prf, otherwise quit with suggestion

include/helper_configure

@@ -62,11 +62,15 @@
     elif [ ${CONFIGURE_SETTINGS} -eq 1 ]; then
 
         # Determine where profiles are stored
-        if [ "${PROFILEDIR}" = "" ]; then
+        if [ -z "${PROFILEDIR}" ]; then
             ${ECHOCMD} "Can not configure Lynis, as profile directory is unknown"
             ExitFatal
         fi
-        if [ "${CUSTOM_PROFILE}" = "" ]; then ${ECHOCMD} "No custom profile found yet."; fi
+        if [ -z "${CUSTOM_PROFILE}" ]; then
+            ${ECHOCMD} "No custom profile found yet."
+            ${ECHOCMD} "Suggestion: create one with 'touch custom.prf' or 'touch /etc/lynis/custom.prf'"
+            ExitFatal
+        fi
 
         FIND=$(echo ${HELPER_PARAMERS} | grep " ")
         if [ ! "${FIND}" = "" ]; then ${ECHOCMD} "Found invalid character (space) in configuration string"; ExitFatal; fi