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

app/stores/AuthStore.js

@@ -63,7 +63,7 @@ class AuthStore {
   };
 
   @action
-  getOauthState = () => {
+  genOauthState = () => {
     const state = Math.random()
       .toString(36)
       .substring(7);
@@ -71,6 +71,12 @@ class AuthStore {
     return this.oauthState;
   };
 
+  @action
+  saveOauthState = (state: string) => {
+    this.oauthState = state;
+    return this.oauthState;
+  };
+
   @action
   authWithSlack = async (code: string, state: string) => {
     // in the case of direct install from the Slack app store the state is