upcoming change in Juju 2.0 to bootstrap arguments

[Ian Booth]

See https://bugs.launchpad.net/juju/+bug/1632919

The order of the cloud/region and controller name arguments will be swapped.

Old:

$ juju bootstrap mycontroller aws/us-east-1

New:

$ juju bootstrap aws/us-east-1 mycontroller
or now
$ juju bootstrap aws/us-east-1

Notice how controller name is optional. It will default to cloud-region.
eg

$ juju bootstrap aws
Creating Juju controller "aws-us-east-1" on aws/us-east-1
...

The only fallout I expect will be for folks like OIL who use scripts will have
to tweak their scripts to swap the arguments. The bootstrap API itself is
unaffected so Python client and other API users will see no difference. It's
just a CLI change.