Async hst components cannot write head contributions

Although document at [1] :

"Asynchronous components cannot contribute hst:headContributions since they are not rendered (they are later async rendered) when the headContributions are written to the html."

we can perhaps for the AJAX javascript included variant do something (ESI/SSI async is most likely impossible). For the AJAX variant, we could write headContributions in the response as well, and try to to inject them in the resulting dom as well. It will most likely also be difficult to know whether to inject them in the head or bottom of the html. This might not be possible. Either way, the javascript that handles the async result into the dom could handle this as well

[1] http://www.onehippo.org/library/concepts/component-development/asynchronous-hst-components-and-containers.html