[enh] urbandictionary xpath engine added

engines.cfg_sample

 
 [bing]
 engine = bing
+language = en-us
 
 [deviantart]
 engine = deviantart
 engine = twitter
 categories = social media
 
+[urbandictionary]
+engine        = xpath
+search_url    = http://www.urbandictionary.com/define.php?term={query}
+url_xpath     = //div[@id="entries"]//div[@class="word"]//a
+title_xpath   = //div[@id="entries"]//div[@class="word"]//span//text()
+content_xpath = //div[@id="entries"]//div[@class="text"]//div[@class="definition"]//text()
+
 [yahoo]
 engine        = xpath
 search_url    = http://search.yahoo.com/search?p={query}