[Icecast] add AAC+ file header to new streams

[Karl Heyes]

oddsock wrote:

> That being said, caching a the AAC+ header is certainly something that 
> can be done in Icecast, heck, it's REQUIRED for streaming ogg vorbis 
> streams (caching the first 3 pages of a vorbis stream - containing 
> codebooks and other critical goodies).

Technically icecast could be configured to cache/send something 
initially if the format is parsed but that is not the case for AAC like 
it is for vorbis.  I doubt that the header in question is constant either.

karl.