FIX: ensures mousetrap is reset with the application (#7569)

app/assets/javascripts/discourse.js.es6

@@ -1,3 +1,4 @@
+/*global Mousetrap:true*/
 import { buildResolver } from "discourse-common/resolver";
 import {
   default as computed,
@@ -15,6 +16,12 @@ const Discourse = Ember.Application.extend({
     paste: "paste"
   },
 
+  reset() {
+    this._super(...arguments);
+
+    Mousetrap.reset();
+  },
+
   getURL(url) {
     if (!url) return url;