message: add execution model setters to agents
diff: @@ -101,6 +101,10 @@ class Agent : public Object {
  behavior_model_ = behavior_model_ptr;
  }
  + void SetBehaviorModel(const ExecutionModelPtr &execution_model_ptr) {
  + execution_model_ = execution_model_ptr;
  + }
  +
  void SetGoalDefinition(const GoalDefinitionPtr &goal_definition) {
  goal_definition_ = goal_definition;
  }
  