all: nest models under accounts in models.yaml

[axw]

jujuclient has been updated so that models.yaml
has the following structure:

controllers:
  <controller>:
    accounts:
      <account>:
        models: ...
        current-model: ...

The output of "list-controllers" and "show-controller"
has been updated to reflect the new structure. Listing
controllers now only shows a current model if there is
a current account for the controller.

The modelcmd package has been updated accordingly.

• a controller command may be initialised without
  a current account, but will error if an attempt
  is made to obtain an API connection without setting
  the current account.
• model command will fail if an attempt is made to
  set the current model, but there is no current
  account for the controller.

There is no way to identify a model for a different
account in a controller; the current account for the
controller is always assumed.

Some minor changes were made to the change-user-password
and create-model commands. The change-user-password
command no longer requires the specified user to exist
in the local jujuclient store. The create-model command
no longer uses configstore, and uses jujuclient exclusively.

(Review request: http://reviews.vapour.ws/r/3952/)

[axw]

$$merge$$

[jujubot]

Status: merge request accepted. Url: http://juju-ci.vapour.ws:8080/job/github-merge-juju