Initial wireless support with ifcfg files

Parsing and converting ifcfg for wireless.
Partial support for multiple networks.
Schema wireless.xml update.
Adding ni_string_contains() utility function
compat: Added initial /sbin/ifup,ifdown,ifstatus
service: enable at install, disable sysconfig-network
updated .gitignore file
wireless: fix for no <network> crash problem
automake: fixed distcheck and install ifup links via rpm
spec: use rpm if to test the _sbindir value
Allow to multiple arguments in system-updater run
Rework updates in preparation for netconfig

1. Remove concept of lease weights, allowing netconfig policies to decide.
2. Handle multiple lease updates.
3. Introduce ni_system_updater_remove() for removal of lease information
   (mainly used by netconfig). Note that full functionality of this
   feature will rely on extension/resolver changes in upcoming patch.
[extensions/system_update] Enable netconfig support for resolver extension

If available, extensions/resolver will use /sbin/netconfig for dns updates.
Otherwise, we fall back to mananging /etc/resolv.conf in the initial
fashion.

Also, incorporating the following fixes/enhancements provided by mt:
- Fixed resolv.conf data parsing in netconfig mode.
- Under netconfig, the netconfig update policies are used.
  Otherwise the extension implements own external policy to
  prefer settings, e.g. static over dhcp or ipv4 over ipv6.
wireless: updates to samples (suse, nanny, wicked)

- Adding new suse ifcfg-wlan0 template to host4
- Adding new wicked wlan0-multi.xml example with multiple
  networks'configuration
- Updating existing nanny and wicked wlan*.xml examples
  to match the schema with <network>
makefile: fix to create systemv dbus service files
Lease state dictates install or remove

Rely on lease state passed in from __ni_system_interface_update_lease()
to determine installation/removal of lease information from the system.
Additionally check the seqno of lease to only install the lease of
interest on update/new lease arrival.
[system_update] Streamline lease updates

- Perform updates as leases are passed to us from ifconfig.c:__ni_system_interface_update_lease().
- Don't disable an updater if an error during install/remove occurs.
makefile: fix to create systemv dbus service files [2]
Added ni_updater_source convenience functions
Added ni_updater_source_array and functions
Chaged updater to use updater source arrays
[system_update] Lease removal cleanup
[doc] Documentation cleanup

Changes by mt, pwieczorkiewicz and kmroz.