Adding DuckDuckGo Zero-click information to Pattern

I have made some simple additions to Pattern to support the DuckDuckGo Zero-click info API (http://api.duckduckgo.com/). I added documentation to the README so it should be self-explanatory (obviously those README changes should be removed from whatever is pulled upstream, but should be helpful right now).

I'll admit that this is not necessarliy adding much new "first-party" information, as DDG itself will mostly return results from Wikipedia, Merriam-Webster, etc. Nonetheless, I like DDG, and I like the format, speed, and simplicity of the results (getting a Wikipedia abstract from DDG is far faster than using the current Wikipedia functions you have, since those pull the entire articles).

I'm sending my work to you as a pull request for consideration to be included in the mainstream Pattern repository. Please let me know if this is something you think is a good idea, and if so what the next steps are. The change is simple and should be mostly complete (unless you want more convenience functions) and just require hopefully minor maintenance as DuckDuckGo itself matures (hopefully leading to more data being available).

Thank you for your time,
soycode