rework dns_spoof plugin to support ANY queries

This pull request enables the dns_spoof plugin to react also if the querytype is ANY as suggested by @torunRuwor in #630.

However this feature required a large rework how the plugin handles the answer creation and the way it's sent onto wire.

It can be easily tested if the etter.dns file is prepared with the following entries:
```
google.de A 127.0.0.1
google.de AAAA 2001:db8::1
google.de MX 127.0.0.2
```
and on the victim computer run the command `host -t ANY -v google.de`.