Use go native embed lib for static assets

Use built in embed library to serve static files instead of the statik library

plugins/webui/static/js/controller.js

@@ -0,0 +1,90 @@
+var app;
+const timeoutMax = 30000;
+const timeoutMin = 1000;
+var timeout = timeoutMin;
+
+function loadContent() {
+  app = new Vue({
+    el: "#app",
+    data: {
+      error: {
+        has_error: false,
+        error_message: ""
+      },
+      state: {
+        output_current: null,
+        output_voltage: 0,
+        output_frequency: 0,
+        output_power: 0,
+        input_current: 0,
+        input_voltage: 0,
+        input_frequency: 0,
+        input_power: 0,
+        battery_current: 0,
+        battery_voltage: 0,
+        battery_charge: 0,
+        battery_power: 0,
+        led_map: [
+          { led_mains: "dot-off" },
+          { led_absorb: "dot-off" },
+          { led_bulk: "dot-off" },
+          { led_float: "dot-off" },
+          { led_inverter: "dot-off" },
+          { led_overload: "dot-off" },
+          { led_bat_low: "dot-off" },
+          { led_over_temp: "dot-off" }
+        ]
+      }
+    }
+  });
+
+  connect();
+}
+
+function connect() {
+  if (window["WebSocket"]) {
+    var conn = new WebSocket(getURI());
+    conn.onclose = function(evt) {
+      app.error.has_error = true;
+      app.error.error_message =
+        "Server not reachable. Trying to reconnect in " +
+        timeout / 1000 +
+        " second(s).";
+
+      console.log(app.error.error_message, evt.reason);
+      setTimeout(function() {
+        connect();
+      }, timeout);
+      timeout = timeout * 2;
+      if (timeout > timeoutMax) {
+        timeout = timeoutMax;
+      }
+    };
+
+    conn.onopen = function(evt) {
+      timeout = timeoutMin;
+      app.error.has_error = false;
+    };
+
+    conn.onmessage = function(evt) {
+      var update = JSON.parse(evt.data);
+      app.state = update;
+    };
+  } else {
+    app.error.has_error = true;
+    app.error.error_message = "Our browser does not support WebSockets.";
+  }
+}
+
+function getURI() {
+  var loc = window.location,
+    new_uri;
+  if (loc.protocol === "https:") {
+    new_uri = "wss:";
+  } else {
+    new_uri = "ws:";
+  }
+  new_uri += "//" + loc.host;
+  new_uri += loc.pathname + "ws";
+  return new_uri;
+}