Ordinarily, this is available via `grunt.util.async`, so it's not necessarily needed here.

That said, the version bundled with grunt is deprecated and may be removed in the future, so it's fine to provide a separate copy.

However I'd prefer to avoid including it this way, better to just require it from within the endpoint itself, or alternatively use a solution like https://github.com/angular/di.js to manage the dependencies (which would be useful anyways because it should help with testing).