Add support for MPEG audio elementary streams in HLS

In the new KitKat HLS solution support for elementary
audio streams was added. According to a comment both AAC
and MPEG audio should be supported, but only AAC is
actually implemented. When streaming an MPEG audio stream
the whole phone would freeze. This commit implements support
for MPEG audio as well.

Change-Id: I083961599d5316b76da9fe47c8561d34569a456d