add-machine fails when using IP in ssh: target

[Andrew Wilkins]

It appears there's an issue with targeting IP addresses in "add-machine ssh:...". We shouldn't be passing an IP into net.LookupIP.

From Matthew Williams:
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I tried bootstrapping in aws then adding a machine supplied by digital ocean. I got an invalid domain error. Any idea what I was doing wrong?

juju add-machine -v ssh:root@162.243.10.110
2013-09-15 20:06:07 INFO juju.provider.ec2 ec2.go:187 opening environment "amazon"
2013-09-15 20:06:12 INFO juju.state open.go:68 opening state; mongo addresses: ["ec2-54-221-71-210.co
mpute-1.amazonaws.com:37017"]; entity ""
2013-09-15 20:06:15 INFO juju.state open.go:106 connection established
2013-09-15 20:06:18 INFO juju.provider.ec2 ec2.go:187 opening environment "amazon"
2013-09-15 20:06:18 ERROR juju supercommand.go:282 command failed: lookup 162.243.10.110: invalid dom
ain name
error: lookup 162.243.10.110: invalid domain name

[Andrew Wilkins (axwalk)]

Note: this only happens when using the non-cgo version of "net".