Feature, upload media to S3 as part of micropub request

Squashed commit of the following:

commit 1f1175a4d944f573868dc2282e62fbd1b4e88b6a
Author: Jonny Barnes <jonny@jonnybarnes.uk>
Date:   Sun Apr 22 18:46:02 2018 +0100

    Fix file upload tests to reflect that we have now inlined the file upload to S3

commit 40d2af5b76e8f390d0275830390dd89ab4d12f54
Author: Jonny Barnes <jonny@jonnybarnes.uk>
Date:   Sun Apr 22 18:45:20 2018 +0100

    Markup the bookmrark test that uses puppeteer, doesn’t play nicely with my old MacBook and let’s me skip that one test

commit bbae1557c87d4d8f3b324abda1a6b8bf66acb8d8
Author: Jonny Barnes <jonny@jonnybarnes.uk>
Date:   Sun Apr 22 17:56:25 2018 +0100

    Inline the S3 upload for media

    Smaller images can then be uploaded by the ProcessMedia job. Inline-ing
    the upload prevents an S3 URL being sent that will initially 404.

tests/Unit/BookmarksTest.php

@@ -11,6 +11,9 @@ use GuzzleHttp\Handler\MockHandler;
 
 class BookmarksTest extends TestCase
 {
+    /**
+     * @group puppeteer
+     */
     public function test_screenshot_of_google()
     {
         $uuid = (new BookmarkService())->saveScreenshot('https://www.google.co.uk');