Post to Slack (#603)

* Migrations

* WIP: Integration model, slack perms / hooks

* So so rough it pains me. Building this new model is revealing just how much needs to be refactored

* Working connect and post

* Cleanup UI, upating documents

* Show when slack command is connected

* stash

* 💚

* Add documents.update trigger

* Authorization, tidying

* Fixed integration policy

* pick integration presenter keys

server/models/index.js

@@ -1,5 +1,6 @@
 // @flow
 import Authentication from './Authentication';
+import Integration from './Integration';
 import Event from './Event';
 import User from './User';
 import Team from './Team';
@@ -12,6 +13,7 @@ import Star from './Star';
 
 const models = {
   Authentication,
+  Integration,
   Event,
   User,
   Team,
@@ -32,6 +34,7 @@ Object.keys(models).forEach(modelName => {
 
 export {
   Authentication,
+  Integration,
   Event,
   User,
   Team,