Fix broken images if octoprint is not at website's root (#134)

* Led status icon : relative URL

Make the URLs for the LED status icons relative, for them to work outside root (with Octoprint URLs like http://example.website/octoprint/ )

Author: Thelm76

octoprint_ws281x_led_status/static/js/ws281x_led_status.js

@@ -15,9 +15,9 @@ $(function () {
         self.torch_toggle = ko.observable(true);
 
         var torch_on_src =
-            "/plugin/ws281x_led_status/static/svg/flashlight.svg";
+            "./plugin/ws281x_led_status/static/svg/flashlight.svg";
         var torch_off_src =
-            "/plugin/ws281x_led_status/static/svg/flashlight-outline.svg";
+            "./plugin/ws281x_led_status/static/svg/flashlight-outline.svg";
 
         self.lights_on = ko.observable(true);
         self.torch_on = ko.observable(false);