Adds a method that allows sending application data through DTLS. Enables handling of received application data when DTLS-SRTP is enabled.

Adds a registerUser() method to SrtpControl. Needed for allowing multiple MediaStream-s to share an SrtpControl.

Throws an exception if deleting or renaming a file fails.

Correctly load jitsi-defaults.properties when running under WebStart

Demotes the logging of the statistics about the sent and received RTCP SR/RR reports because they are too frequent.

Reported by Thomas Kuntz.

Because now RtpdumpStream doesn't use the rtpdump timestamp to sync
the stream. Now the sync use the timestamp of rtp packet directly, with
the timebase computed from the framerate/samplerate of the Format.

Also change the static method that create rtpdump MediaDeviceImpl :
it now takes a MediaFormat, so that it can get the clock rate of the
format (used in the timebase).

but provide a static method creating a AudioMediaDeviceImpl
or MediaDeviceImpl (for video) for convenience instead.

classes of the rtpdump package now use RtpdumpPacket, that extends RawPacket
(so the parsing is done by RawPacket).

Also fix a javadoc typo.