Bulk export (#684)

* First pass (working) collection export to zip

* Add export confirmation screen

* 👕

* Refactor

* Job for team export, move to tmp file, settings UI

* Export all collections job

* 👕

* Add specs

* Clarify UI

server/mailer.test.js

@@ -1,5 +1,5 @@
 /* eslint-disable flowtype/require-valid-file-annotation */
-import { Mailer } from './mailer';
+import Mailer from './mailer';
 
 describe('Mailer', () => {
   let fakeMailer;