Adds identification of poltergeist's in presence.

resources/prosody-plugins/mod_muc_poltergeist.lua

 	    from = component.."/"..nick,
    }):tag("x", { xmlns = MUC_NS }):up();
 
+    p:tag("bot", { type = "poltergeist" }):up();
     p:tag("call_cancel"):text(nil):up();
     p:tag("call_id"):text(username):up();