For mpd codes, rename dash_packager to edash_packager; for media codes,
add namespace edash_packager.
Change-Id: I1120e6110c734cd02bdbe15f1cf7abddcdfdd7ea
Add BandwidthEstimator to estimate the required bandwidth for the
segments.
Also includes unit test for the change.
Change-Id: I28262424e2ed6ceebdf81e2b11dcd67feba1d68c