Added memfile without persistence to set_config unit tests. This eliminates
the tests attempting to create the csv file.

Updated copyrights.

Fixed misspelling.

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

The timers are scheduled in the ControlledDhcpvXSrv instances. The
unit tests are located in the kea_controller_unittest.cc.

 - ChangLog updated (b10-dhcp4 => DHCPv4 server)
 - stand-alone mode removed in Kea4,Kea6
 - getInstance() used instead of server_
 - ctrl_dhcp4_srv.cc: one stringstream instance now shared by all error messages
 - ctrl_dhcp4_srv.h: comments cleaned up
 - Added log message for received configuration
 - kea_controller.cc: Unnecessary header/using namespace removed
 - *.json files are now cleaned up in src/bin/dhcp4/tests
 - added comment that explains lack of tests for Bundy backend
 - kea_controller_unittest.cc now uses the same filename everywhere

Changes also applied to Kea6 (where applicable).

 - files renamed to {kea,bundy}_controller.cc
 - Daemon::init() is now void
 - status variable removed from main
 - added unit-tests for broken configs

- config-reload command added
- config and command handlers cleaned up
- files renamed
- Majority of the backend code is now common
- Added unit-test for config-reload command

- added --with-kea-config=JSON,BIND10 added to configure.ac
- JSON-file config backend added for b10-dhcp6
- Config file can now be read from a JSON file

Still have lots to do.
Some of these marked with TODO indicating needing further work
(but better than it was before).

mostly in documentation or in comments

reviewed by muks via jabber

includes output changes for two isc_throw.

reviewed by jelte via jabber.

Changes some log message descriptions and some
function arguments and some output.

In particular, the new configuration is merged with the existing
configuration to trigger the full reconfiguration of the server. This is
to satisfy dependencies between various configuration values.

The DHCP6 server had the lease database configuration temporarily
hard-coded.  With the introduction of database configuration
parameters, that is no longer needed.

Also fix some issues from the review.

Before this change, the choice of lease manager was set in
ControlledDhcpv6Srv.  This means that unit tests for that code
always used the MySQL lease manager (if present).  This change
ensures that unit tests always use the Memfile manager.