- checkpoint 2: continuing refactoring of voice app

...c/main/java/org/bigbluebutton/voice/conf/Application.java

...main/java/org/bigbluebutton/voice/conf/sip/CallAgent.java

...in/java/org/bigbluebutton/voice/conf/sip/CallManager.java

...va/org/bigbluebutton/voice/conf/sip/ClientConnection.java

...bigbluebutton/voice/conf/sip/ClientConnectionManager.java

...c/main/java/org/bigbluebutton/voice/conf/sip/SipPeer.java

...java/org/bigbluebutton/voice/conf/sip/SipPeerManager.java

...va/org/bigbluebutton/voice/conf/sip/SipRegisterAgent.java

...igbluebutton/voice/conf/sip/SipRegisterAgentListener.java

...utton/voice/conf/sip/exception/PeerNotFoundException.java

...ice/src/main/java/org/zoolu/sip/provider/SipProvider.java