[Monitoring.h] Use a defined type instead of a raw type.
[Param] Consolidate special host IDs to one file.

this patch also fixes the overlap of special IDs.
[Params.h] Add comments to make it easy to see groups of constants.
[Params] Consolidate special IDs to Param.h

This patch also fixes overlap of special trigger IDs.
Merge pull request #527 from project-hatohol/arrange-fixed-host-ids

Arrange fixed host ids