Fix for broken replication

Fix for broken replication has been added to mysql_monitor.
Both Slave_IO  and Slave_SQL threads must be running in order to assign
the SERVER_SLAVE status but If only Slave_IO is running let’s assign
the master_id to current server and continue building the replication
tree; if no slaves at all the master will be still available.
The “detect_stale_master” option has been added, its default is 0.
If set to 1 the monitor will keep the last detected master even if the
replication setup is completely not working, i.e. both Slave_IO  and
Slave_SQL threads are not running: this applies only to the server that
was master before.
After monitor or MaxScale are restarted and the replication is still
stopped or not configured there will be no master because it’s not
possible to compute the replication topology tree.
Merge branch 'MAX-232' into 232-bis

Conflicts:
	server/core/server.c
	server/include/server.h
New entry point added to all monitors

New entry point added to all monitors
MySQL monitor detects broken replication and a new option 'detect_stale_master' has been added.

- Monitor automatically builds the replication topology tree if at least Slave_IO thread is running in slaves and the master server will be available.

- If the replication is stopped or configuration removed the previos master server may be still available with detect_stale_master=1
	The SERVER_STALE_STATUS bit is added to the server->status field

Monitor diagnostic routine print all new status descriptions