Detect if frisbeed fails to startup due to not being able to bind to the port and retry with a different address/port if so.
Detect if frisbeed fails to startup due to not being able to bind to
the port and retry with a different address/port if so.

Also, check for immediate failure of the TBBackground call so that we can
return at error if it fails (most likely because someone forgot to do a
post-install after boss-install and it cannot write the indicated logfile)

nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome