External freeswitch

Made a Pull request as requested in the ticket: http://code.google.com/p/bigbluebutton/issues/detail?id=1359

This branch contains also the solution to the following ticket: http://code.google.com/p/bigbluebutton/issues/detail?id=1355

If there's something that has to be modified please let me know and I'll do the changes as soon as possible and then I'll notify you.

Alex