This reverts commit 8d0324f4, reversing
changes made to 9257854f.

Revert trac3732a merge because config was reused by command stuff.

Conflicts:
	doc/guide/dhcp4-srv.xml
	src/bin/dhcp4/tests/Makefile.am
	src/lib/stats/stats_mgr.h
	src/lib/stats/tests/stats_mgr_unittest.cc

 - UnixCommandSocket does not use ElementPtr anymore
 - strerror() is now used correctly
 - Doxygen comments corrected and updated

 - log messages in commandReader are now errors, not warnings
 - missing doxygen comment added

 - Extra logging messages for socket failures
 - strerror() is now reported when encountering low-level errors
 - fcntl, accept return codes are now verified
 - minor tweaks in CtrlDhcpv4SrvTest.command* unit-tests.

 - StatsMgr::getStatName() implemented.

 - CommandSocket, UNIXCommandSocket and ConnectionSocket classes added.
 - Updated unit-test to use

Conflicts:
	src/bin/dhcp4/tests/dhcp4_test_utils.cc

 - comments in StatsMgr improved
 - added unit-test for CfgMgr::clear() and stats
 - copyright years updated

    Adds kea-admin unit tests for PosgreSQL lease-dump

Added extra wording about restarting PostgreSQL.

Minor cleanup. Lease dump tests for both MySQL and PostgreSQL
now use multiple timestamps values.

 - {update,remove}Statistics moved from CfgMgr to SrvConfig,CfgSubnets4

 - packet names updated in User's Guide
 - StatsMgr now uses int64_t, not uint64_t
 - StatsMgr::generateName() added
 - DISCOVER => DHCPDISCOVER