There are a few fixes here for #665

• TinyMCEBuilder must use absolute URIs for embeddings like images because the resulting page content "moves around" in the site hierarchy and the links break.
• Permalinks must be absolute. The "navigate to permalink" link in the editor broke.
• Local redirects must be relative to the site root
• Site config needs to fix up a root that doesn't end in a slash. That's the most fundamental issue.