JSON: Added check command as selector for host and service queries

This commit adds the check command as a select for host and service count
and list queries in both the object and status JSON CGI.
JSON: Added event handler as selector for host and service queries

This commit adds the event handler as a selector for host and service count
and list queries in both the object and status JSON CGI.
JSON Object: Added master host as selector for dependency queries

This commit adds master host as a selector for the host and service
dependency count and list queries. The master host is the non-dependent
host.