Start some refactoring around the Bus interface

git-svn-id: https://svn.apache.org/repos/asf/cxf/trunk@1483985 13f79535-47bb-0310-9956-ffa450edef68
Start refactoring some Bus things

git-svn-id: https://svn.apache.org/repos/asf/cxf/trunk@1483987 13f79535-47bb-0310-9956-ffa450edef68
Remove the CXFBusImpl class

git-svn-id: https://svn.apache.org/repos/asf/cxf/trunk@1483988 13f79535-47bb-0310-9956-ffa450edef68