This is WIP commit for pgxc_ctl.   Now it can configure all the master/slave,
promote gtm slave and reconnect gtm_proxy to the new master, including
configuration update.

Updated files are:

	modified:   contrib/pgxc_ctl/config.c
	modified:   contrib/pgxc_ctl/coord_cmd.c
	modified:   contrib/pgxc_ctl/datanode_cmd.c
	modified:   contrib/pgxc_ctl/do_command.c
	modified:   contrib/pgxc_ctl/do_shell.c
	modified:   contrib/pgxc_ctl/gtm_cmd.c
	modified:   contrib/pgxc_ctl/monitor.c
	modified:   contrib/pgxc_ctl/monitor.h
	modified:   contrib/pgxc_ctl/pgxc_ctl.bash
	modified:   contrib/pgxc_ctl/pgxc_ctl_log.c
	modified:   contrib/pgxc_ctl/utils.c