dhcp6: do not fail on read-only root-fs (bnc#885625)
duid: don't try to load duid in a save call
leases: fallback to statedir on read-only fs (bnc#885625)
Merge pull request #318 from mtomaschewski/ro-root-fs

dhcp6: do not fail on read-only root-fs (bnc#885625)