compat: blacklist all and default interface names
addrconf: avoid unwanted updates, update flag fixes

- Splitted addrconf updater type and update bitmap
- Defined the update flags in the schema and fixed
  to initialize to all known flags instead to ~0.
- Read several dhclient variables from suse ifcfg
  config such as update hostname (bnc#865325) and
  also diverse timing variables (not all used yet).
- Fixed extensions/hostname to verify its state and
  drop obsolete state to allow to switch to use a
  hostname from different lease (reconfiguration).