Addint SRTP and rtcp-mux + few bugfixes

[iivalchev]

Hi Bjorn,

This are the changes I have made. Please note that we use java-bells in a simple tool used only for testing. I didn't have much time when I was creating that so the changes made are far from the state I would like them to be. As usual we are running on tight schedule, but hope I would have the time to spend in refactoring and improving the library, as of now there isn't a good Java librirary for Jingle that would provide you with the full stack required for streamming.

Best regards, Ivan

[bejayoharen]

Thanks so much for this contribution! It's been a while since I've looked at this project, so it might require some time for me to look this over, but a quick skim looks good.