Fixed patch references in the changelog to include patch nr.

- Applied fix by Jiri Slaby to not crash in interface discovery
when the interface address is NULL, which has been introduced
by the infiniband support patch (bsc#909189,bsc#870535).
[+ 0027-dhcp-4.2.x-handle-ifa_addr-NULL.909189.patch]

- fix bashisms in dhcprelay script

- Applied contrib/ldap/dhcpd-conf-to-ldap patch by Ales Novak to
reorder config to add all global options or option declarations
to the dhcpService object instead to create new service object
(bsc#886094,ISC-Bugs#37876).
[+ 0022-dhcp-4.2.x-contrib-conf-to-ldap-reorder.886094.patch]
- Applied an upstream patch by Thomas Markwalder adding missed
mapping of SHA TSIG algorithm names to their constants to enable
hmac-sha1, hmac_sha224, hmac_sha256, hmac_sha384 and hmac_sha512
authenticated dynamic DNS updates (bsc#890731, ISC-Bugs#36947).
[+ 0023-dhcp-4.2.x-ddns-tsig-hmac-sha-support.890731.patch]
- Decline IPv6 addresses on Duplicate Address Detection failure
and stop client message exchanges on reached MRD rather than
at some point after it. Applied fedora patches by Jiri Popelka
and added DAD reporting via exit 3 to the dhclient-script and
a fix to use correct address variables in the DEPREF6 action
(bsc#872609,ISC-Bugs#26735,ISC-Bugs#21238).
[+ 0024-dhcp-4.2.x-dhcpv6-decline-on-DAD-failure.872609.patch,
+ 0025-dhcp-4.2.x-dhcpv6-retransmission-until-MRD.872609.patch]
- Applied backport patch by William Preston avoiding to bind ddns
socket in the server when ddns-update-style is none (bsc#891655).
[+ 0026-dhcp-4.2.x-disable-unused-ddns-port-in-server.891655.patch]
- Applied patch for the contrib/ldap/dhcpd-conf-to-ldap script
fixing subclass statement handling (bnc#878846,[ISC-Bugs #36409])