minor change in debugging messages
add assign_ipv6_addresses_to_accounts

Created assign_ipv6_addresses_to_accounts.pl, based on the original
assign_ipv6_addresses_to_ldap. assign_ipv6_addresses_to_accounts can
directly assign full IPv6 prefixes to accounts whereas
assign_ipv6_addresses_to_ldap used to assign IPv6 to the unit and then
tried to split the prefixes to accommodate all the accounts.
Merge branch 'sch-experiment' into temp
rename assign_ipv6_addresses_to_ldap.pl to _to_units.pl