Add support for several config options

[kiwiz]

New:

• key
• router
• update-static-leases
• subnet-mask
• ddns-domainname
• use-host-decl-names

Updated:

• allow/deny - Allow passing an array of values like so:

  deny:
  - bootp
  - client-updates
  - declines
  - leasequery

[kiwiz]

Thanks for the review. :]

I've split out the formatting changes into a separate commit (e5e39be). W.r.t. the allow/deny changes, dhcpd was giving me an error if the clause wasn't in the pool block.

[0xf10e]

Ah, OK. Did I miss the mention of moving accept/deny into the pool-part of the template? ;)

[kiwiz]

Fixed up & split an unrelated change into a separate commit.

[0xf10e]

:+1:

[aboe76]

@kiwiz thanks for this

[kiwiz]

:+1: