Added quality of life functions

* Ability to use full path for image path
*  Ability to configure the wait time between images
*  Added protection from escaping the image directory

config.json.example

@@ -1,6 +1,7 @@
 {
     "PORT":8000,
     "IMAGE_DIR":"images",
+    "IMAGE_TIMEOUT":Minutes the image is shown,
     "WeatherProvider":"HomeAssistant or MetNO",
     "METNO_LAT":"MetNO Weather GPS Latitude",
     "METNO_LON":"MetNO Weather GPS longitude",