Make posts.htmlize() smarter

[echolabstech]

This method was originally written to wrap html snippets to look like a real web page. Now we have the ability to fetch complete web pages from RSS feeds. However In some use cases, such as when the RSS feed fails to download a web page, the old wrapping behavior will still be necessary.

Requirements: htmlize() should be either return complete webpages

1. wrap snippets in a web page (what we already do)
2. return complete web page