Store PSK Identity in the DTLS Session

Once the DTLS session is started successfully the applicative level will
want to know the used identity.

So I'm storing it in the DTLS session
Merge pull request #8 from jvermillard/identity-in-dtls-session

Store PSK Identity in the DTLS Session
missing files for PR #7
Merge pull request #9 from jvermillard/missing-files

missing files for PR #7