Replace Java UUID slow and blocking

[hrosa]

The JDK UUID Generator is slow and is blocking MGCP threads when setting up media resources for new calls. The root cause is CNAME and SSRC generators of the RTP Connection.

Must replace JDK UUID with a faster, non-blocking UUID generator. Probably will need better support for ssrc collision in MS, especially if we adopt faster but weaker UUID generator (like time-based).