Filecrop & Yacy engine

Hi,

I added two engines :

* http://www.filecrop.com/ : it allows to search for files. I did not found any json API so the I parse the html we receive (using HTMLParser : http://docs.python.org/2/library/htmlparser.html). I added a File category in my engines.cfg.

* Yacy : http://yacy.net/ (it's a peer to peer search engine) : the thing is that you need to have a yacy instance running to use it. Their search portal demo ( http://search.yacy.net/) was not working when I did the dev. Yacy provides a json API,

I don't know if these 2 engines will be useful, I implemented them mostly to play a bit with searx and discover it. Seems pretty cool so far, really easy to use.