iteritems() was dropped in recent Python3 releases and items() is compatible
with Python 2.7.

Change-Id: I7e9267036d473b68c5344ed50304030e6985f27c

Change-Id: I1bffc95697a5765f47c33dbf262e4efb10472c82

Change-Id: I8f2a66c6edafc425794d7cedc8b9217df7ee5951

Change-Id: I83f09d01ff047bd61e044977b1eae0e2d0442b5c

Parameter purge_hosts will enforce whole /etc/hosts file, removing entries
that are not defined in model except defaults for both IPv4 and IPv6 localhost
and hostname + fqdn.

It's good to use this option if you want to ensure /etc/hosts is always in a
clean state however it's not enabled by default for safety.

Change-Id: Ieb219b2dd494d5a66ecc52a2ec00dd5157ee2b7a