Koenig - Rename server-side cards

refs #9311
- match card names to the new generic Koenig card names introduced in TryGhost/Admin@95a0686

core/server/lib/mobiledoc/cards/card-markdown.js

@@ -0,0 +1,4 @@
+// this card is just an alias of the `markdown` card which is necessary because
+// our markdown-only editor was using the `card-markdown` card name
+let markdownCard = require('./markdown');
+module.exports = markdownCard;

core/server/lib/mobiledoc/cards/hr.js

@@ -1,5 +1,5 @@
 module.exports = {
-    name: 'card-hr',
+    name: 'hr',
     type: 'dom',
     render(opts) {
         return opts.env.dom.createElement('hr');

core/server/lib/mobiledoc/cards/html.js

@@ -1,7 +1,7 @@
 'use strict';
 
 module.exports = {
-    name: 'card-html',
+    name: 'html',
     type: 'dom',
     render(opts) {
         let html = `<div class="kg-card-html">${opts.payload.html}</div>`;

core/server/lib/mobiledoc/cards/image.js

@@ -1,5 +1,5 @@
 module.exports = {
-    name: 'card-image',
+    name: 'image',
     type: 'dom',
     render(opts) {
         var img = opts.env.dom.createElement('img');

core/server/lib/mobiledoc/cards/markdown.js

@@ -1,5 +1,5 @@
 module.exports = {
-    name: 'card-markdown',
+    name: 'markdown',
     type: 'dom',
     render: function (opts) {
         var converters = require('../converters'),