gulp.task('img-tin', function () {
    return watch('src/img/**/**/*.*', function () {
        gulp.src('src/img/**/**/*.*')
            .pipe(plumber())
            .pipe(newer('app/img'))
            .pipe(tinpng('KuffE3fffJSVgF4mnffWpfff26xXfffA_l'))
            .pipe(gulp.dest('app/img'));
    });
});