add rtpdump file for testing purposes (for the rtpdumpfile CaptureDevice).
add patch and corresponding patched version of libjitsi (and some
modifs activating dtls in the hammer) that enable dtls.

The patch comments out some cipher suites in the server and client impl,
ciphers that should have been available only for dtls v1.2 (but the impl use
dtls v1.0).