Merge lp://qastaging/~frankban/juju-gui/bug-1229939-service-set into lp://qastaging/juju-gui/experimental

Reviewers: mp+187544_code.launchpad.net,

Message:
Please take a look.

Description:
Fix settings update in juju-core.

When sending ServiceSet requests, the GUI included
a Config parameter where juju-core expects an
Option one.
While I was looking at that code, I decided instead to
switch to the newer ServiceUpdate API call, which
handles both map[string]string and YAML settings.

QA:
- deploy and expose the GUI in a juju-core env;
- switch to this branch:
     juju set juju-gui
juju-gui-source=lp:~frankban/juju-gui/bug-1229939-service-set
- try to change settings (e.g. juju-gui-debug);
- refresh.

The settings viewlet should reflect the changes and,
after a while (after config-changed runs),
the new settings should be applied.

https://code.launchpad.net/~frankban/juju-gui/bug-1229939-service-set/+merge/187544

(do not edit description out of merge proposal)

Please review this at https://codereview.appspot.com/13900044/

Affected files (+52, -61 lines):
   A [revision details]
   M app/store/env/go.js
   M app/store/env/sandbox.js
   M test/test_env_go.js
   M test/test_inspector_settings.js
   M test/test_sandbox_go.js
   M test/test_service_config_view.js

This bug has been fixed here: https://codereview.appspot.com/13917043/ .

https://codereview.appspot.com/13900044/