[3589] Created an object to hold the option configuration.
[3589] Added equals function to the CfgOption class.
[3589] Two option configurations can be now merged together.
[3589] Added function to copy the options configuration.
[3589] Add options confiuration object to the SrvConfig object.
[3589] Moved subnet-specific option configuration to CfgOption class.
[3589] Option data configuration parsers store parsed data into cfgmgr.
[3589] Refactored merge/copy to mergeTo/copyTo in CfgOption.
[3589] CfgOptionDef::copy overrides old configuration.
[3367] Implemented unit test for checking ciaddr.
[3367] Set 0 ciaddr for DHCPOFFER and DHCPNAK.
[3537] Kea logs that the packet contains invalid giaddr/hops combination.
[3367] Missing doxygen tag added.
[3560] Basic implementation of the Host class.
[3560] Implemented rest of the functions in the Host class.

Also, added documentation to the Host class.
[master] Merge branch 'trac3537'
[master] Added ChangeLog entry for #3537.
[3367] Removed excessive call to setCiaddr in DHCPv4 server.
[3367] Moved OptionalValue class to the util library.
[3560] Added new accessors and modifiers to the Host class.