Add script editor (#393)

* Add script editor

* Cleanup

js/automation-editor/trigger/mqtt.js

@@ -0,0 +1,37 @@
+import { h, Component } from 'preact';
+
+import { onChangeEvent } from '../../common/util/event';
+
+export default class MQTTTrigger extends Component {
+  constructor() {
+    super();
+
+    this.onChange = onChangeEvent.bind(this, 'trigger');
+  }
+
+  /* eslint-disable camelcase */
+  render({ trigger }) {
+    const { topic, payload } = trigger;
+    return (
+      <div>
+        <paper-input
+          label="Topic"
+          name="topic"
+          value={topic}
+          onChange={this.onChange}
+        />
+        <paper-input
+          label="Payload (Optional)"
+          name="payload"
+          value={payload}
+          onChange={this.onChange}
+        />
+      </div>
+    );
+  }
+}
+
+MQTTTrigger.defaultConfig = {
+  topic: '',
+  payload: '',
+};