Fix the bug where jitsi-hammer was closing its connection to the
XMPP server and the MUC when a new user was added to the Jitsi Meet room.

This error was caused by an old JingleAction.java file, where the Jingle action
addsource wasn't defined (and cause JingleIQ to throw a error, that made smack
close its connection (of course no log were printed....)).

Jitsi Hammer may need to handle these addsource/removesource IQ in the future
minor update (some minor fixes)
fix little typo
temporary fix for the bug where when an audio CaptureDevice was
used for the audio stream (here AudioSilenceMediaDevice), the program
was taking 100% of one core of the CPU.

The fix was to set the MediaDirection of the streams to SENDONLY
(RECVONLY also avoid the issue, but the hammer doesn't send data, so not good).
--> SENDRECV seems to trigger the 100% of a core issue.