Collecta search plugin-in for Strophe

Requires strophejs, http://github.com/metajack/strophejs

This plug-in manages a set of streaming searches to the Collecta API.
Each search is a pubsub subscription to Collecta.  Atom payloads will
be delivered to the user-supplied callback function as new results
become available.

 Plug-in methods:
   subscribe(query, options)
     start watching a query

     query - string containing desired search query
     options - object with possible properties: api_key, query, rate_limit,
       context_count, and score_threshold. see Collecta api docs for 
       details on most of these. context_count is the number of historical
       items to fetch for context. api_key and query are required; others 
       are optional.

   unsubscribeAll()
     unsubscribe from all searches