[#35,!517] Removed DDNS params from D2ClientCfg and tests

[#35,!517] Removed DDNS params from D2ClientCfg and tests

src/lib/dhcpsrv/d2_client_cfg.*
    D2ClientConfig - removed DDNS params

src/lib/dhcpsrv/parsers/dhcp_parsers.cc
    D2ClientConfigParser::parse() - removed DDNS params

src/lib/dhcpsrv/parsers/simple_parser4.cc
    SimpleParser4::GLOBAL4_PARAMETERS
    SimpleDefaults SimpleParser4::GLOBAL4_DEFAULTS
    - added DDSN params

src/lib/dhcpsrv/tests/cfgmgr_unittest.cc
    Updated calls to D2ClientCfg ctor

src/lib/dhcpsrv/tests/d2_client_unittest.cc
    Removed DDNS and hostname params from tests

src/lib/dhcpsrv/tests/d2_udp_unittest.cc
    Updated calls to D2ClientCfg ctor

src/lib/dhcpsrv/tests/dhcp_parsers_unittest.cc
    Removed DDNS and hostname params from tests