function mapImageResources (rootDir, subDir, type, resourceName) {
    const pathMap = {};
    const globOptions = { cwd: path.join(rootDir, subDir), onlyDirectories: true };
    glob.sync(type + '-*', globOptions).forEach(drawableFolder => {
        const imagePath = path.join(subDir, drawableFolder, resourceName);
        pathMap[imagePath] = null;
    });
    return pathMap;
}
Gets a map containing resources of a specified name from all drawable folders in a directory.