Websocket Support (#937)

* Atom / RSS meta link

* Spike

* Feeling good about this spike now

* Remove document.collection

* Remove koa.ctx from all presenters to make them portable outside requests

* Remove full serialized model from events
Move events.add to controllers for now, will eventually be in commands

* collections.create event
parentDocument -> parentDocumentId

* Fix up deprecated tests

* Fixed: Doc creation

* documents.move

* Handle collection deleted

* 💚

* Authorize room join requests

* Move starred data structure
Account for documents with no context on sockets

* Add socket.io-redis

* Add WEBSOCKETS_ENABLED env variable to disable websockets entirely for self hosted
New installations will default to true, existing installations to false

* 💚 No need for promise response here

* Reload notice

package.json

@@ -49,7 +49,7 @@
     ]
   },
   "engines": {
-    "node": "8.11"
+    "node": ">= 8.11"
   },
   "repository": {
     "type": "git",
@@ -148,6 +148,9 @@
     "sequelize-cli": "^5.4.0",
     "sequelize-encrypted": "0.1.0",
     "slug": "^1.0.0",
+    "socket.io": "^2.2.0",
+    "socketio-auth": "^0.1.1",
+    "socket.io-redis": "^5.2.0",
     "string-replace-to-array": "^1.0.3",
     "style-loader": "^0.18.2",
     "styled-components": "^4.2.0",