IE11 issue with ES6 option

Hi,
we have an issue on IE11.

Steps to reproduce

Install the SDK using npm install ripe-sdk (latest version 1.2.3).
Import ./node_modules/ripe-sdk/dist/ripe-min.js.
The page breaks on IE11.

Analysing the project seems that gulp build task copy the ripe-min from src to dist using uglifyjs with an option for ES6.

ripe-sdk/gulpfile.js

Lines 19 to 32 in 444cafd

    
           gulp.task("build-js", () => { 
        
               return gulp.src(paths.scripts) 
        
                   .pipe(uglifyes({ 
        
                       mangle: false, 
        
                       ecma: 6 
        
                   })) 
        
                   .pipe(replace("__VERSION__", _package.version)) 
        
                   .pipe(size()) 
        
                   .pipe(size({ 
        
                       gzip: true 
        
                   })) 
        
                   .pipe(gulp.dest("dist")) 
        
                   .pipe(count("## js files copied")); 
        
           });

related to d5dc23d

Just to let you know that I tested d5dc23d on IE11 and it works. Thanks

	gulp.task("build-js", () => {
	return gulp.src(paths.scripts)
	.pipe(uglifyes({
	mangle: false,
	ecma: 6
	}))
	.pipe(replace("__VERSION__", _package.version))
	.pipe(size())
	.pipe(size({
	gzip: true
	}))
	.pipe(gulp.dest("dist"))
	.pipe(count("## js files copied"));
	});