Display document views (#849)

* Display who has viewed a document in the header

* Add overflow, display of WHEN last viewed
Cleanup old document attributes
Add firstViewedAt, lastViewedAt to API response

* Cleanup

* Added: API documentation for views endpoints

* Include views for deleted users

app/stores/ViewsStore.js

@@ -0,0 +1,21 @@
+// @flow
+import { filter, orderBy } from 'lodash';
+import BaseStore from './BaseStore';
+import RootStore from './RootStore';
+import View from 'models/View';
+
+export default class ViewsStore extends BaseStore<View> {
+  actions = ['list'];
+
+  constructor(rootStore: RootStore) {
+    super(rootStore, View);
+  }
+
+  inDocument(documentId: string): View[] {
+    return orderBy(
+      filter(this.orderedData, view => view.documentId !== documentId),
+      'lastViewedAt',
+      'desc'
+    );
+  }
+}