dhcp4: add support for additional DHCPv4 request options

For now, push the values from ifcfg to the dhcp4 request structures. We
will use them later.
schema: add additional DHCPv4 options
client: parse additional DHCPv4 options to xml
Merge pull request #183 from kmroz/dhcp4-extra-options-rc
compat: correctly init dhcp recover/release lease

Initialize default settings at the right places.
Fixed to not reset global settings while reading
the per-interface settings from suse ifcfg files.
compat: include appconfig.h for wicked defaults
Merge branch 'sle12' (bnc#867078,bnc#866732)
arp: return parsed arp packet op in host order
utils: properly adjust array in remove actions
Merge pull request #188 from mtomaschewski/array-remove

utils: properly adjust array in remove actions
utils: use proper index in ni_string_array_remove
socket: use proper array in socket array activate
Merge pull request #189 from mtomaschewski/array-remove

fixed array remove typo and socket array activate
client: added ipv4 arp verify and notify utilities
arp: use more likely to work gratuitous ARP requests
address: allow to mark address tentative/duplicate
addrconf: mark static lease addresses tentative
ipv6: corrected to apply inverted ipv6.enable flag
arp: verify ipv4 addresses by default (fate#314399)

Enabled arp verify for ipv4 addresses by default (RFC 5227)
and send arp notify when requested in suse ifcfg variables
CHECK_DUPLICATE_IP(=yes) and SEND_GRATUITOUS_ARP(=no).
compat: fixed to disable ip for BOOTPROTO none