chore: Auto reload frontend of client is out of date (#1270)

* Move editor version to header
Add editor version check for API endpoints

* fix: Editor update auto-reload
Bump RME

* fix: Only redirect if editor header exists

* lint

server/api/middlewares/editor.js

@@ -0,0 +1,17 @@
+// @flow
+import { type Context } from 'koa';
+import pkg from 'rich-markdown-editor/package.json';
+import { EditorUpdateError } from '../../errors';
+
+export default function editor() {
+  return async function editorMiddleware(ctx: Context, next: () => Promise<*>) {
+    const editorVersion = ctx.headers['x-editor-version'];
+
+    // As the client can only ever be behind the server there's no need for a
+    // more strict check of version infront/behind here
+    if (editorVersion && editorVersion !== pkg.version) {
+      throw new EditorUpdateError();
+    }
+    return next();
+  };
+}