Remove deprecated option dnssec-lookaside as DLV was disabled

[pecharmin]

Problem

named configured by inkblot-bind reports a warning on configuration check:

$ named-checkconf -j -z
/etc/bind/named.conf:14: dnssec-lookaside 'auto' is no longer supported

Environment

mod 'inkblot-bind', '7.4.0'

Solution

Remove deprecated named option dnssec-lookaside from config template as ISC's DLV was decommissioned on 30.09.2017:

• https://bind9.readthedocs.io/en/latest/reference.html#options-statement-definition-and-usage -- dnssec-lookaside
• https://www.isc.org/blogs/dlv/

[kenyon]

Fixes #153