[TIMOB-19645] CLI: Builder.generateAppIcons ignores existing assets

	function createAppIconSet(next) {
		var appIconSetDir = path.join(this.buildDir, 'Assets'),
			missingIcons = [
			// Square44x44Logo
			{
				description: 'Square44x44Logo.png - Used for logo',
				file: path.join(appIconSetDir, 'Square44x44Logo.png'),
				width: 44,
				height: 44,
				required: true
			},

			// Square71x71Logo
			{
				description: 'Square71x71Logo.png - Used for logo',
				file: path.join(appIconSetDir, 'Square71x71Logo.png'),
				width: 71,
				height: 71,
				required: true
			},

			// Square150x150Logo
			{
				description: 'Square150x150Logo.png - Used for logo',
				file: path.join(appIconSetDir, 'Square150x150Logo.png'),
				width: 150,
				height: 150,
				required: true
			}
		];
		this.generateAppIcons(missingIcons, next);
	}