test refactoring for SOAPDispatcher: move custom assertions into separate section
SOAPDispatcher should generate correct SOAP faults if a handler returns a SOAPError
test refactoring: rename parameter for internal assertion so it reflects the actual SOAP naming
SOAP 1.1 fix: get_error_response() now uses specified fault code
support fault actors/roles in get_error_response()

Actually "actor" is a SOAP 1.1 (in 1.2 they call that "role") but I was unable to come up with a better name for both variants which still reflects the actual meaning so I just went with the SOAP 1.1 name.