utils: Add ni_string_clear()
wireless: Remove secrets as soon as they are used
util: Add ni_try_mlock()

ni_try_mlock() checks for errno. It accepts EPERM error to continue,
when user is not allowed to lock memory.
wireless: mlock the network structure
wireless: catch failing network object allocation
Merge pull request #225 from pwieczorkiewicz/wireless-passwd

wireless: clean and protect passwd
ifstatus: fixed address indenting in verbose mode
dbus: added ni_dbus_dict_get/add_uuid helpers
leases: added ni_netdev_get_lease_by_uuid helper
dhcp6: apply config uuid to lease and offer early
dhcp4: apply config uuid to lease and offer early
bridge: do not flood debug about port object path
model: fixed to check callback allocation and uuid
status: show only available leases with uuid
lease: added lease flags and show them in status
addrconf: moved name/tape functions to addrconf.h
addrconf: moved ni_system_update_from_lease to system.h
utils: added ni_format_bitmap utility
Merge pull request #226 from mtomaschewski/mt/dhcp4or6

status: show only available leases with uuid
client: Split check_prio and raw arguments