expanding the functionality a bit

I apologize for the commits that changed line feeds so it's harder to read what the changes were.  Here's a summary of what I added for a project that I'm working on.  Some of these things probably should be made configurable, but I didn't have time yet to add that.  If you're interested in pulling this stuff into your repo and want it configurable, I'll add that.

- call google safe browsing API before scraping
- new constructor that doesn't scrape immediately so you can set additional namespaces, etc before scraping
- if opengraph data isn't present, go back and scrape for other meta attributes and image tags
- handle following redirects with cookies for sites like nytimes.com that require it

Thanks,
Rob