**Do you want to request a *feature* or report a *bug*?**
bug
**What is the current behavior?**
poi think of `webp` as img
**If the current behavior is a bug, please provide the steps t…
The readme says that this package is compatible with node >= 4 but actually is compatible only with node >= 6.
Since it's quite easy to support also node 4, @ranisalt would you consider a PR to add b…