Generate the Wide Windows Icons correctly

[peterlgarland]

When generating the icons, the Windows Wide Icons are still square, and this causes Cordova build to fail for Windows 10 Apps.

The Wide size should be 310 x 150 (744 x 340 at 2x). But square 310 x 310 (744 x 744 at 2x) images are produced instead.

[anonymuos1]

Same problem, fix it please! Thank you!