For mpd codes, rename dash_packager to edash_packager; for media codes,
add namespace edash_packager.
Change-Id: I1120e6110c734cd02bdbe15f1cf7abddcdfdd7ea
Also add support for format tags.
Also change default fragment_duration to 10s, i.e. to have the same
value as --segment_duration. So by default, only one fragment per
(sub)segment is generated.
Change-Id: I21123723c3998b656037a397eb7b58b3d91721bb