Watchdog for MaxScale

Provide a watchdog utility for MaxScale that runs as a process on the MaxScale server and continuously monitors MaxScale process
1. It should detect that MaxScale is hung and crash with signal 6 (using watchdog?)
2. It should have the option to generate a core dump upon the crash
3. When there are multiple MaxScale nodes in HA configuration, other Maxscale nodes watchdog should detect if the Maxscale node with the setting of active (i.e. passive=0) went down and elect one of the other MaxScale nodes to be active and assign the elected MaxScale node with passive=0