agent client/server doc: unsubscribe method callback signal on release
agent client/server doc: unsubscribe method callback signal on release

01org/cloudeebus,enzuguri/cloudeebus,enzuguri/cloudeebus,lizardo/cloudeebus-devel,pohly/cloudeebus,fpaut/cloudeebus,modulexcite/cloudeebus,monsieurmona/cloudeebus,pohly/cloudeebus,monsieurmona/cloudeebus,fpaut/cloudeebus,pohly/cloudeebus,enzuguri/cloudeebus,01org/cloudeebus,lizardo/cloudeebus-devel,01org/cloudeebus,fpaut/cloudeebus,lizardo/cloudeebus-devel,modulexcite/cloudeebus,modulexcite/cloudeebus,monsieurmona/cloudeebus