The custom opcua server bind option is added and it can be
parced with command line option -a or server_ip_address=.
If no ip address is mentioned, then server is listening on all interfaces

modified:   cli.h
modified:   keep_alive_publisher.h
modified:   keep_alive_subscriber.h
modified:   server.c

Test: Program is tested

See merge request !17

See merge request !16

Add a new CLI option to set the timeout after which without a heart beat a dependant coupler is considered DOWN.

Make network address url data type configurable so we can support both IPv4 / IPv6 multicast from  CLI.