[TIMOB-19347] Windows: Ti.Network.HTTPClient.send fails when arg object has non-string/Blob values

Our current code assumes that the JSObject has string property names (which is valid) and either String or Ti.Blob values. It needs to handle other value types and convert them into strings. The following works on iOS/Android, but fails on Windows:

var datas = {
        'authenticatestring': Alloy.Globals.authenticateString,
        'functionName': 'registerNewReceiver',
        'apiVersion' : Alloy.Globals.serverApiVersion,
        'languageId' : Alloy.Globals.serverLanguage,
        'deviceId' : Alloy.Globals.deviceId,
        'purchaseId' : 9846598
    };
    httpClient.send();

This is because our code take the numeric value for 'purchaseId' and since it's not a string assumes it's a Blob and attempts to pull a native Ti.Blob object out of it.