Merge branch 'trac3665' Add processing for LFC

This branch adds the main processing functions for
lease file cleanup.  We added

code in lease_file_loader.h to write leases from storage to a file

code in lfc_controller to read leaes into storage from a file
and then write the storage out to a file (using lease_file_loader)
and then to move the files around to get the names correct.

Conflicts:
	ChangeLog

diff --cc ChangeLog
index 9b9fe381d81d0dc7a6f3f3fa23c44faf5862734d,1ebd68c6b83c6cfdb61327e015b5605bee251d2c..37dd5d9dd31d90f9f15e8cfaf1381815655431c7
--- 1/ChangeLog
--- 2/ChangeLog
+++ b/ChangeLog
@@@ -1,23 -1,9 +1,29 @@@
 -xxx.  [func]          sar
++887.  [func]          sar
+       A new process, kea-lfc, has been added. It is meant to
+       be periodically executed by the DHCPv4 and DHCPv6 servers
+       to remove redundant information from the lease files.
+       See http://kea.isc.org/wiki/LFCDesign#no1 for the design.
+ 
 +886.  [func]          tomek
 +      libdhcpsrv: Allocation Engine now uses statically assigned
 +      addresses when it allocates leases for the DHCPv6 clients.
 +      (Trac #3563, git b86b24fd011c0617515d62b7091d56fdfd1a7360)
 +
 +885.  [func]          tomek
 +      Information-Request (stateless mode) in DHCPv6 is now supported.
 +      (Trac #2949, git 3185d229c39ed4660e9bc98a7f4a9d0dfbe64a04)
 +
 +884.  [func]          marcin
 +      The DHCPv6 server configuration now allows for defining a pool
 +      for prefix delegation in which prefixes do not match a
 +      subnet prefix.
 +      (Trac #3647, git 5455d96cbf773e678bd6b1c3e31bfdeb617e6c13)
 +
 +883.  [bug]           marcin
 +      libdhcpsrv: Prevent infinite loops in the allocation engine,
 +      when the address pool becomes exhausted.
 +      (Trac #3692, git f1e464558c89a6dc88ab28a25dd14a65fee62578)
 +
  882.  [func]          sar
        A utility class has been added which handles writing and
        deleting pid files as well as checking if the process with