improve config file behaviour

.gitignore

@@ -1 +1 @@
-config.conf
+config.cfg

ezmlm-export-subscribers.sh

@@ -2,9 +2,9 @@
 
 cd $(dirname $0)
 
-DIR="$(grep ^DIR config.conf | awk -F= '{ print $2 }')"
-EXPORT="$(grep ^EXPORT config.conf | awk -F= '{ print $2 }')"
-DESC="$(grep ^DESC config.conf | awk -F= '{ print $2 }')"
+# Test if config.cfg exists and set needed variables
+if [ ! -e config.cfg ]; then echo "Missing config.cfg file. Edit and rename config.cfg.sample"; exit 1; fi
+source config.cfg
 
 echo "$DESC" > $EXPORT
 echo "" >> $EXPORT