Markdown card (#7568)

Refs #7429
- Added mobiledoc card, this uses the mobiledoc editor from within Ghost. In the future we'll pull this out and replace it with a textarea as the preview is too small to fit in the content.
- Made the HTML editor a codemirror editor (pulled in from ghost-admin to save duplicating libraries).
- Ghost-Admin now passes the paths for the ghost-api and the image directory for tools.
- Fixed the scrolling issue.

package.json

@@ -46,7 +46,7 @@
     "express-hbs": "1.0.3",
     "extract-zip-fork": "1.5.1",
     "fs-extra": "0.30.0",
-    "ghost-editor": "0.0.10",
+    "ghost-editor": "0.0.11",
     "ghost-gql": "0.0.5",
     "glob": "5.0.15",
     "gscan": "0.0.15",