Get image file extension

src/freedombone-app-gnusocial

@@ -954,6 +954,11 @@ function install_gnusocial_theme {
         exit 356723
     fi
 
+    if [ $GNUSOCIAL_BACKGROUND_IMAGE_URL ]; then
+        filename=$(basename "$GNUSOCIAL_BACKGROUND_IMAGE_URL")
+        GNUSOCIAL_BACKGROUND_IMAGE_URL_EXT="${filename##*.}"
+    fi
+
     gnusocial_config_file=/var/www/$GNUSOCIAL_DOMAIN_NAME/htdocs/config.php
     if ! grep -q "addPlugin('Qvitter')" $gnusocial_config_file; then
         GNUSOCIAL_WELCOME_MESSAGE=$(echo $GNUSOCIAL_WELCOME_MESSAGE | sed "s|\$GNUSOCIAL_DOMAIN_NAME|$GNUSOCIAL_DOMAIN_NAME|g")