feat: Document presence indicator (#1114)

* Update websockets to allow joining document-based rooms

* dynamic websocket joining

* emit user.join/leave events when entering and exiting document rooms

* presence storage

* feat: frontend presence store

* lint

* UI updates

* First pass editing state

* refactoring

* Timeout per user/doc
lint

* Document data loading refactor to keep Socket mounted

* restore: Mark as viewed functionality
Add display of 'you' to collaborators

* fix: Socket/document remount when document slug changes due to title change

* Revert unneccessary package update

* Move editing ping interval to a shared constant

* fix: Flash of sidebar when loading page directly on editing mode

* separate document and revision loading

* add comments for socket events

* fix: Socket events getting bound multiple times on reconnect

* fix: Clear client side presence state on disconnect

* fix: Don't ignore server side error
Improved documentation

* More comments / why comments

* rename Socket -> SocketPresence

* fix: Handle redis is down
remove unneccessary join

* fix: PR feedback

app/stores/ViewsStore.js

@@ -1,5 +1,5 @@
 // @flow
-import { filter, orderBy } from 'lodash';
+import { filter, find, orderBy } from 'lodash';
 import BaseStore from './BaseStore';
 import RootStore from './RootStore';
 import View from 'models/View';
@@ -18,4 +18,13 @@ export default class ViewsStore extends BaseStore<View> {
       'desc'
     );
   }
+
+  touch(documentId: string, userId: string) {
+    const view = find(
+      this.orderedData,
+      view => view.documentId === documentId && view.user.id === userId
+    );
+    if (!view) return;
+    view.touch();
+  }
 }