Code review comment for lp:~thumper/juju-core/machine-worker

Reviewers: mp+203460_code.launchpad.net,

Message:
Please take a look.

Description:
Add a worker to keep disk files up to date

Added the machine environment worker which watches
the environment config and will write changes to the
disk as needed.

A new end point was added on the client and server side
that is just called "Environment", which provies the common
environment watcher.

The only gotcha in this is that if the worker is running on
machine 0 for a local provider, it shouldn't attempt to modify
system files. There are tests for this.

The two files on disk that are currently being kept up
to date with this are:
  /home/ubuntu/.juju-proxy
  /etc/apt/apt.conf.d/42-juju-proxy-settings

https://code.launchpad.net/~thumper/juju-core/machine-worker/+merge/203460

Requires:
https://code.launchpad.net/~thumper/juju-core/fix-uniter-proxy-env-vars/+merge/203459

(do not edit description out of merge proposal)

Please review this at https://codereview.appspot.com/57600043/

Affected files (+580, -1 lines):
   A [revision details]
   M cmd/jujud/machine.go
   M environs/cloudinit/cloudinit.go
   A state/api/environment/environment.go
   A state/api/environment/environment_test.go
   A state/api/environment/package_test.go
   M state/api/state.go
   A state/apiserver/environment/environment.go
   A state/apiserver/environment/environment_test.go
   A state/apiserver/environment/package_test.go
   M state/apiserver/root.go
   M utils/apt.go
   A worker/machineenvironmentworker/machineenvironmentworker.go
   A worker/machineenvironmentworker/machineenvironmentworker_test.go
   A worker/machineenvironmentworker/package_test.go