function updateFile(filename, content, exists) {
	fs.ensureDirSync(path.dirname(filename));
	fs.writeFileSync(filename, content);
	log.added(`${exists ? 'Update' : 'Create'} ${filename}`);
}
Write a file if the content was changed and print a message.
@param {string} filename
@param {string} content
@param {boolean} exists