Add event handlers to main and pool config - Enhancement

[mergwyn]

• Module version: 4.0.1

The event handlers are currently only supported for dhcp::host (see #216). These handlers can also exist globally in dhcpd.conf or in the pool definition dhcpd::pool and dhcpd::pool6.

I propose to replicate the PR and add 3 new optional parameters to the relevant classes:

on_commit
on_release
on_expiry

So two questions:

• Is there any reason not to do this?
• Is there a recommended pattern for including an ERB template fragment in multiple places, or should I just duplicate the 20 or so lines of template code (and associated test code) where needed?