[C++] Removed unneeded forward declaration (RequestCallerFactory)
[C++] Removed unneeded forward declaration (RequestCallerFactory)

Change-Id: I0bdf55d627e5fd441e68a6a71d3e03a8210eed53

clive-jevons/joynr,bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr,clive-jevons/joynr,clive-jevons/joynr,clive-jevons/joynr,bmwcarit/joynr,bmwcarit/joynr,clive-jevons/joynr,clive-jevons/joynr,bmwcarit/joynr,bmwcarit/joynr