Revision 518741

Start work to improve role handling and SOAP version handling.

* Introduce SOAPVersion interface, which lets us get at things like namespace URI and attribute name constants.  Add a getVersion() accessor to SOAPHeaderBlock interface.

* Introduce a "RolePlayer" interface which allows something to indicate that it operates as the ultimate destination (or not), and any custom roles that it supports.  This allows us to decouple role support from Axis2, but still have it in Axiom.

* Introduce a Checker (see SOAPHeaderImpl.java) which gets headers based on a RolePlayer's roles.

* Tests for the above.

* Also removed a few unnecessary "public abstract" modifiers on interface methods.