Add pydoc documentation to akanda driver modules

This patch provides pydoc documentation for the following akanda driver
modules:

arp
base
bird
dnsmasq
metadata
ping

Basic documentation has been provided for all methods, but some are
missing specific type, param, and rtype docstrings.
A (dict) mapping of generic to physical hostname, e.g., {'ge0': 'eth0', 'ge1': 'eth1'}