Supports Transport Layer Encryption

[mycrl]

This issue is for documenting the progress of adding transport layer encryption to turn-rs, and related issues.

TLS

Implementing tls inside rust is a very simple thing to do, and there is a very mature ecosystem to take advantage of.

DTLS

Implementing dtls is a bit more complicated, and if I can't find a mature library inside crates.io, I have no choice but to implement it myself from scratch.

[DDreame]

hi, i have create a pull request about TLS #107 , please review.

[mycrl]

The benefits of supporting transport layer encryption are so small and minimal that it's forced me to rethink the need to include transport layer encryption at this time.

None of the major current clients actually support transport layer encryption unless tested with coturn's test suite.

Adding transport layer encryption would bring a lot of extra work, but no significant benefit, so I'm putting this feature on hold for now, to be added in a subsequent release.