Updated linphone, use new incoming call script, and added a ringtone

Created by: bhdouglass

Stuff Done:

• Updated linphone to call an external script on an incoming call
• Added script to launch the app when a call is incoming
• Added default wav ringtone (linphone doesn't seem to support ogg, so the system ringtones are out)

Needs Work:

• Support for url handling is needed (the new script calls the app with a linphone:// uri to let it know there is an incoming call)
• Support for a "ringing" view, so that people actually know there is a call coming (visually)