Enhancement Request: Facilitate "Catch All"

[bridgeythegeek]

As a testing/development DNS server, it would be useful to allow some kind of "catch all". For example, it might be useful for dnserver to respond to a request for an A record with a specific IP address (e.g. 10.11.12.13) regardless of what domain was actually queried.

Use cases might be:

1. Debugging DNS functionality.
2. Analysing malware where the domain to be requested is not yet known, but we want to redirect to a server under the analyst's control.

An example toml entry might be:

[[zones]]
host = '__CATCH_ALL'
type = 'A'
answer = '10.11.12.13'