fix bug 1721604

[hmlanigan]

Description of change

Juju bootstrap cli results should be the same as running bootstrap interactive. If bootstrap, cli only, doesn't specify a region, but finds one to use, use it for config too.

QA steps

One:

1. set region config for an openstack cloud, suggest network since you can't bootstrap without it most of the time.
2. juju bootstrap

Two:
bootstrap a cloud without regions, such as localhost

Documentation changes

n/a

Bug reference

https://bugs.launchpad.net/juju/+bug/1721604

[jujubot]

Can one of the admins verify this patch?

[hmlanigan]

bug 1721604: bootstrap succeeds with interactive command fails otherwise

[hmlanigan]

$$merge$$

[jujubot]

Status: merge request accepted. Url: http://ci.jujucharms.com/job/github-merge-juju