Make org.jinglenodes.JingleNodesPlugin configurable

Version 1
    1. Stun server "stun.xten.com" is not workable at my area, it should be configurable. I change the default value to "stun.stunprotocol.org".
    2. The range of random UDP port is between 30000 to 50000, it should be configurable because of enterprise firewall policy.
    3. The attachment is the source file, please merge it to the next version. Thank you.