Now reads from stdin if no hosts.dat or --hostlist

Example:
    cat hosts.dat | horde /tmp/test /tmp/test

Fixes bug if --hostlist is passed junk like:
    horde --hostlist 1,2,3,,,\#test /tmp/test /tmp/test

Fixes bug --hostlist passing blank list of hosts like:
    ./horde --hostlist '' /tmp/test /tmp/test