Fix hooks toggling

New ember-data serializers send data without a model key in the payload
by default, so instead of what API expects:

    {
      "hook": {
        "id": 1,
        "active": true
      }
    }

it would send:

    { "id": 1, "active": true }

Because of that we need to change how hooks are serialized.

Furthermore, API V2 returns just "result: true" after a successful
request to change a hook, so we need to return something meaningful from
the adapter's updateRecord in order to make ember-data happy.

app/adapters/hook.js

@@ -0,0 +1,9 @@
+import ApplicationAdapter from 'travis/adapters/application';
+
+export default ApplicationAdapter.extend({
+  updateRecord(store, type, snapshot) {
+    return this._super(...arguments).then( (data) => {
+      return { hook: { id: snapshot.id } };
+    });
+  }
+});

app/serializers/hook.js

@@ -0,0 +1,7 @@
+import ApplicationSerializer from 'travis/serializers/application';
+
+export default ApplicationSerializer.extend({
+  serialize(snapshot, options) {
+    return { hook: this._super(...arguments) };
+  }
+});