src/bin/dhcp6/ctrl_dhcp6_srv.h
src/bin/dhcp6/ctrl_dhcp6_srv.cc
    ControlledDhcpv6Srv::commandSetConfigHandler() - new method to process
    the set-config command.

    ControlledDhcpv6Srv::processCommand() - call new set-config handler

    ControlledDhcpv6Srv::processConfig() - added logic to apply logging
    and commit configuration after  successful reconfig

    ControlledDhcpv6Srv::ControlledDhcpv6Srv(uint16_t port) - added registration
    of set-config command

    ControlledDhcpv6Srv::~ControlledDhcpv6Srv() - unregisters set-config command

src/bin/dhcp6/json_config_parser.cc
    configureCommandChannel() - extracted logic to reconfigure command channel
    to its own fucntion

src/bin/dhcp6/kea_controller.cc
    configure() - removed logic to apply logging and commit config, now done
    in ControlledDhcpv6Srv::processConfig()

src/bin/dhcp6/tests/ctrl_dhcp6_srv_unittest.cc
    TEST_F(CtrlChannelDhcpv6SrvTest, set_config) - new test to exercise the
    set-config command