Get interfaces ip

[targuan]

Fix #204
As proposed in the issue by ktbyers I used show ip[v6] interface.

I changed the documentation of get_interfaces_ip in the code as N/A was not accepted on link-local ipv6 prefix_length because it was not an integer. I replaced N/A by 64 which seems to be the prefix length of such addresses.

[coveralls]

Coverage increased (+1.9%) to 71.797% when pulling 8cdc7c2 on targuan:get_interfaces_ip into eaaaec6 on napalm-automation:develop.

[bewing]

Might this be more readable as

interfaces = {intf: details for intf, details in interfaces.items() if details['ipv4'] != {}}

?

[ktbyers]

Yes, I think I would probably change this slightly to something like:

            if(line[0] != ' '):
                ipv4 = {}
                interface_name = line.split()[0]
            m = re.match(INTERNET_ADDRESS, line)
            if m:
                ip, prefix = m.groups()
                ipv4.update({ip: {"prefix_length": int(prefix)}})
                interfaces[interface_name] = {'ipv4': ipv4}

i.e. only add it to 'interfaces' if there is a positive match

[ktbyers]

FYI, we agreed on /10 for link-local addresses after reviewing some documents on it:

napalm-automation/napalm-base#304

A bit of ambiguity on whether we should use /64 or /10 for this.

[ktbyers]

Only other comment I have is that I need to verify how we handle secondary addresses by default. In other words, whether we do anything to differentiate between a secondary or primary address in the returned data structure.

[targuan]

Thanks for your feebacks.
I've updated my PR according to your remarks.

[coveralls]

Coverage increased (+1.9%) to 71.797% when pulling d06c7b9 on targuan:get_interfaces_ip into eaaaec6 on napalm-automation:develop.

[ktbyers]

The secondary address form is correct. So this should be right.