Started implementing a proper arp module

And I mostly cleared the sample, this will really just be a sample..

Signed-off-by: Toon Schoenmakers <nighteyes1993@gmail.com>
The arp module actually logs now

Also fixed a couple of bugs in the database pool.

Signed-off-by: Toon Schoenmakers <nighteyes1993@gmail.com>
Made the table and columns for the arp module configurable

Signed-off-by: Toon Schoenmakers <nighteyes1993@gmail.com>
Started working on the arp prober

Had to remodel some APIs yet again. You really find out what you're
missing in your APIs once you actually start to use them. This arp
prober is NOT ready for production just yet, as the range it'll probe
is currently hardcoded. And there is no way to disable it from the
configuration just yet.

Signed-off-by: Toon Schoenmakers <nighteyes1993@gmail.com>