Ensure that wifi interface is set in config file

src/freedombone-utils-wifi

     update_wifi_adaptors
     if [ ! $IFACE ]; then
         # Don't try to configure wifi if there are no adaptors
+        remove_config_param "WIFI_INTERFACE"
         return
     fi
+    write_config_param "WIFI_INTERFACE" "$WIFI_INTERFACE"
 
     if [ -f $WIFI_NETWORKS_FILE ]; then
         rm $WIFI_NETWORKS_FILE

src/freedombone-wifi

 IFACE=
 IFACE_SECONDARY=
 
+source /usr/share/${PROJECT_NAME}/utils/${PROJECT_NAME}-utils-config
 source /usr/share/${PROJECT_NAME}/utils/${PROJECT_NAME}-utils-wifi
 
 function show_help {
             shift
             WIFI_INTERFACE=${1}
             wifi_interface_specified=1
+            write_config_param "WIFI_INTERFACE" "$WIFI_INTERFACE"
             ;;
         -t|--type)
             shift
         exit 872356
     fi
     WIFI_INTERFACE=$IFACE
+    write_config_param "WIFI_INTERFACE" "$WIFI_INTERFACE"
 fi
 
 if [ $WIFI_DISABLE ]; then
     disable_wifi $WIFI_DISABLE
+    remove_config_param "WIFI_INTERFACE"
     exit 0
 fi