Added config options to be passed to libxmljs when parsing request XML. Fixes #15.

lib/config.coffee

@@ -19,6 +19,7 @@ exports.DEBUG_DEVICES = {} # {'202BC1-BM632w-8KA8WA1151100043' : true}
 exports.DEVICE_ONLINE_THRESHOLD = 4000
 exports.RETRY_DELAY = 300
 exports.IGNORE_XML_NAMESPACES = false # Traverse XML using element's local name only
+exports.LIBXMLJS_OPTIONS = {} # Options passed directly to libxmljs
 
 exports.MONGODB_OPTIONS = {
   db : {