Update Common-Media-Client-Data implementation

Created by: wilaw

The CMCD specification has now completed development at CTA and is available as CTA-5004. It has some changes compared to the draft version used for the initial implementation within dash.js. This issue is a request to bring the dash.js implementation up to spec with the published version. The final v1 verison can be found here:

https://docs.google.com/document/d/1S_Dj_aHVnbWnjeJYMfLU1D6tZoqYdgHT1stfznBvxig/

Changes from version implemented in dash.js

1. Query arg changed from 'Common-Media-Client-Data' to 'CMCD'
2. DeviceID key deprecated
3. Keys are now ordered alphabetically
4. New 'ot' object types added , now one of [m,a,v,av,i,c,tt,k,o]
5. Measured throughput, requested maximum throughput, deadline and buffer length must now be rounded to the nearest unit of 100 to reduce fingerprinting entropy.
6. Version key should only be reported if it is != 1
7. New keys added:
   1. 'startup' - su
   2. 'top bitrate' - tb
   3. 'buffer starvation' - bs
   4. 'buffer length' - bl (you can stop reporting 'dl' and instead report this value)