Quick #TiAlloy fix for windows being positioned under the status bar on #iOS7

alloy.js

// For iOS7 only, set the window's top to 20 so they start under the status bar.
Alloy.Globals.windowTop = (OS_IOS && parseInt(Ti.Platform.version[0], 10) >= 7) ? 20 : 0;

app.tss

"Window[platform=ios]": {
    top: Alloy.Globals.windowTop
}

tiapp.xml

<ti:app>
    <ios>
        <plist>
            <dict>
                <key>UIStatusBarStyle</key>
                <!-- Use the 'new' light style to get the iOS6-like white text -->
                <string>UIStatusBarStyleLightContent</string>
            </dict>
        </plist>
    </ios>
</ti:app>