Hummingbird: Defer & Async Options for JS

Are there any plans to add options to inject "async" or "defer" attributes to Javascript files combined and minifed by Hummingbird and called in the HTML?

This would be for achieving higher scores in optimization tests like Google PageSpeed and YSlow as well as any actual speed benefits.

Positioning scripts helps, but but being able to easily and selectively async and defer each script would be a nice feature as well.