apiserver/provisioner: Mask out secret env attrs

apiserver/provisioner: Mask out secret env attrs

This changes the provisioner API EnvironConfig()
call to mask out any secret attributes before
returning the config to non-manager agents.
The environment manager agents still get everything.

This closes off a security issue with LXC provisioner
having access to the environment configuration and
its secrets via the API.

Live tested on EC2 successfully.

https://code.launchpad.net/~dimitern/juju-core/147-apiprovisioner-blank-env-secrets/+merge/187738

Requires: https://code.launchpad.net/~dimitern/juju-core/146-apiprovisioner-addresses/+merge/187719

(do not edit description out of merge proposal)

[dimitern, 2013-09-26 11:49:26]

Please take a look.

[jameinel, 2013-09-26 13:10:37]

LGTM given it is the same as the previous submisison which had already been
approved.

[jameinel, 2013-09-26 13:12:01]

On 2013/09/26 13:10:37, jameinel wrote:
> LGTM given it is the same as the previous submisison which had already been
> approved.

I do still have the question why we set the values to "not available" rather
than just deleting them. I guess so Env creation doesn't complain about missing
entries?

[dimitern, 2013-09-26 13:24:01]

On 2013/09/26 13:12:01, jameinel wrote:
> On 2013/09/26 13:10:37, jameinel wrote:
> > LGTM given it is the same as the previous submisison which had already been
> > approved.
> 
> I do still have the question why we set the values to "not available" rather
> than just deleting them. I guess so Env creation doesn't complain about
missing
> entries?

Setting them to something is needed for validation. And since this is temporary,
it'll go away soon (when the provisioner is properly refactored).

[dimitern, 2013-09-26 16:03:33]

Please take a look.