[Server][DBClientUser] Use HostgroupIdType typedef.

In some source code, Host"Grp" and Host"Group" are used.
I'll fix these name change "Hostgroup".
[Client][HatoholHostgroupPrivilegeEditDialog] Fix wrong globalscope
name.
[Server][FaceRest] Change the way of showing numberOfAllowedHostgroups.

In previous way (8595a7b revision), when value of numberOfAllowedHostgroups
variable is 1, this function checks hostgroupId. But current implementation
allows ALL_HOST_GROUPS and all hostgroup ID. As a result, value of
numberOfAllowedHostgroups variable is value of numberOfHostgroups
variable + 1.