CHANGE: numeric constants to enumerated strings

Based on the advice given in the multi-group consultation round, I 
propose that we confirm the proposal made on January 10, based on the 
suggestion by Tab Atkins on December 16, and declare that the 
PeerConnection and MediaStreams APIs will use enumerated strings, not 
integers with associated constants, in all its state variables and other 
parameters that can take a limited set of values, and that the editors 
be instructed to apply this change at their discretion.

If anyone wishes to discuss this issue further, please reply to this 
message.
Given the amount of discussion already had on this subject, silence will 
be taken as consent.

                   Harald, for the chairs