Code review comment for lp:~thumper/juju-core/agent-config-formatters

Reviewers: mp+183074_code.launchpad.net,

Message:
Please take a look.

Description:
Add the formatter concept to agent config.

In order to decouple the internal structure of the agent config from how
it is
stored on disk, we introduce formatters. They are responsible for
moving the
internal config to and from a serialization format.

The existing format is called "format 1.12", as that is the stable
release
that the format was introduced.

Some of the methods are purposefully trivial at this stage, and they are
flushed out in the next branch.

https://code.launchpad.net/~thumper/juju-core/agent-config-formatters/+merge/183074

(do not edit description out of merge proposal)

Please review this at https://codereview.appspot.com/13237050/

Affected files:
   A [revision details]
   M agent/agent.go
   A agent/format-1.12.go
   A agent/format-1.12_whitebox_test.go
   A agent/format.go
   A agent/format_whitebox_test.go