src/bin/dhcp4/dhcp4_messages.mes
        - Added new log message DHCP4_SUPPLY_HOSTNAME

    src/bin/dhcp4/dhcp4_srv.cc
        - Dhcpv4Srv::processClientName() - pushed lack of host option in the
        client request down into processHostoption()

        - Dhcpv4Srv::processHostnameOption() - modified to support the new name
        replacement modes

    src/bin/dhcp4/tests/fqdn_unittest.cc
        - NameDhcpv4SrvTest:: testReplaceClientNameMode() - new method which
        tests a server's handling of a single client packet for a given
        replace-client-name mode.

        - TEST_F(NameDhcpv4SrvTest, replaceClientNameModeTest) - new test which
        exercises the permutations of client packets and replace-client-name
        modes.