androidmedia: Set KEY_IS_ADTS when using adts aac streams

Submitted by Edward Hervey @bilboed

Link to original bug (#741241)

Description

Currently the androidmedia aac decoders state that they can consume ADTS aac (in addition to raw packetization).

When this happens, we also need to set the KEY_IS_ADTS to 1 on the media format, otherwise some implementations will barf at the stream (they assume it's raw and not in adts).

http://developer.android.com/reference/android/media/MediaFormat.html#KEY_IS_ADTS