[TIMOB-19819] iOS: Disable ATS in builtin KitchenSink by default

Currently we need to disable iOS9 App Transport Security (ATS) in the builtin KitchenSink (titanium_mobile/demos/KitchenSink) whenever we want to test any ticket related to webview, httpclient, etc. As we disable ATS in our SDK as well, we should change this setting in the Titanium.plist of the Xcode project. *Example:*

var win = Ti.UI.createWindow();
win.add(Ti.UI.createImageView({image: "http://dummyimage.com/600x400/000/fff"}));
win.open();

*Expected behavior:* The image loads. *Actual behavior:* An ATS error is thrown:

App Transport Security has blocked a cleartext HTTP (http://) resource load since it is insecure. Temporary exceptions can be configured via your app's Info.plist file.

*Solution:*

    <key>NSAppTransportSecurity</key>
    <dict>
        <key>NSAllowsArbitraryLoads</key>
        <true/>
    </dict>