[TIMOB-13691] TiAPI: Ti.Network.HTTPClient ondatastream prototype doesn't fire

When i using *Ti.Network.createHTTPClient* to create a *HTTPClient*, i wanna display upload progress on my app, the *ondatastream* event was bound like below:

var xhr = Ti.Network.createHTTPClient();
xhr.ondatastream = function(e){
    // progressing...
};

but *ondatastream* event was never ever fired, i was confused by this condition, WTF... finally, the solution is that you should only bind *ondatastream* like these:

var xhr = Ti.Network.createHTTPClient({
    ondatastream: function(e){ ... }
});

that's really ridiculous， i guess your guys forgot to implement the prototype of *ondatastream* for HTTPClient(or something else like getter and setter of property *ondatastream*). can you fix it? we really wanna use it like:

var xhr = Ti.Network.createHTTPClient();
xhr.ondatastream = function(e){
    // progressing...
};

{color:red}but not:{color}

var xhr = Ti.Network.createHTTPClient({
    ondatastream: function(e){ ... }
});

regards && thx.