[Server][FaceRest] Add const prefix and reference variable on
addHostgroupIdToListMap function parameter.
[Server][FaceRest] Change the way to store MapList.
[Server][FaceRest] Fix iterator name.

I missed a mistake.
[Server][FaceRest] Fix iterator name.

I missed a mistake.
[Server][FaceRest] Use the HostroupJsonArray class.

But in currently, I found a bug that output data (e.g.: trigger) is
duplicated. I'll fix this.