Mirror option to set packages repo when building images

src/freedombone-image

 # Whether sites are accessible only within a Tor browser
 ONION_ONLY="no"
 
+# Where to fetch packages
+MIRROR='http://httpredir.debian.org/debian'
+
 mesh_router_setup_script() {
     # create a setup script for a mesh router
     mesh_script_filename=$1
     shift
     PROJECT_REPO="$1"
     ;;
+    -m|--mirror)
+    shift
+    MIRROR="$1"
+    ;;
     *)
     # unknown option
     ;;
     SSH_PORT="$SSH_PORT" \
     ONION_ONLY="$ONION_ONLY" \
     IMAGE_NAME="$IMAGE_NAME" \
-    PROJECT_REPO="$PROJECT_REPO"
+    PROJECT_REPO="$PROJECT_REPO" \
+    MIRROR="$MIRROR" \
+    BUILD_MIRROR="$MIRROR"
 
 if [ ! "$?" = "0" ]; then
     echo $'Build failed'