BUG-614: split out RpcServiceMetadata

RpcServiceMetadata is just another holder, no reason to define it in
xtend.

Change-Id: Ic069a9698e47a347e634289c7a96fac20c2a3d3f
Signed-off-by: Robert Varga <rovarga@cisco.com>
Merge "BUG-614: split out RpcServiceMetadata"