initial bitrate API, default starting bitrate, ABR rule improvments.
Created by: dsparacio
KoshinM contributions Adds ability to set initial bitrate per media type, Default starting quality is nearest to 1000 kbps Quicker switch to a better quality
AkamaiDash contributions Moved ABR rule switch limiting into each rule so that each rule could be tuned individually instead of all rules being limited under one time value. Removed limit switch rule for context and samples. Moved rule evaluation back to validate above blocking code so that all ABR rules are always being executed. Again set limited to how fast the rule runs inside the individual rule. Made sure that all the initial bitrate APIs work as intended after these changes.