NA BMI: make BMI honor attempts to bind to specific IPs
NA BMI: make BMI honor attempts to bind to specific IPs

let BMI choose port if unspecified

- empty port specification is passed straight to BMI
- at addr_to_string() time use new get_info variant available in BMI
  master to query port and construct a reachable string

mercury-hpc/mercury,mercury-hpc/mercury,mercury-hpc/mercury,mercury-hpc/mercury