Merge pull request #6550 from QuincyLarson/fix/sample-watermark-certs

update sample certificate images and fix a couple other onboarding as…

challenges/03-back-end-development-certification/back-end-development-certificate.json

@@ -8,7 +8,7 @@
       "title": "Claim Your Back End Development Certificate",
       "description": [
         [
-          "http://i.imgur.com/sKYQhdG.jpg",
+          "http://i.imgur.com/8v3t84p.jpg",
           "An image of our Back End Development Certificate",
           "This challenge will give you your verified Back End Development Certificate. Before we issue your certificate, we must verify that you have completed all of the back end development projects. You must also accept our Academic Honesty Pledge. Click the button below to start this process.",
           ""
@@ -95,7 +95,7 @@
       "nameEs": "Reclama tu certificado de desarrollo Full Stack",
       "descriptionEs": [
         [
-          "http://i.imgur.com/sKYQhdG.jpg",
+          "http://i.imgur.com/8v3t84p.jpg",
           "Una imagen que muestra nuestro certificado de desarrollo Full Stack",
           "Este desafío te otorga tu certificado autenticado de desarrollo Full Stack. Antes de que podamos emitir tu certificado, debemos verificar que has completado todos los Bonfires, Ziplines y Basejumps. También debes aceptar nuestro Juramento de honestidad académica. Pulsa el botón siguiente para iniciar este proceso..",
           ""