Support for more comprehensive harvesting mode vs binary safe-mode.

https://bugs.launchpad.net/juju-core/+bug/1345553
Thanks for the discussion and leeway. I did speak with someone in IRC (name escaping me atm) regarding this, and they said to go ahead and do it. I think I'd rather get the ball rolling and encourage people to follow suite than to wait for a big-bang type change. I've tacked a TODO onto the comment to let people know they should begin utilizing this pattern.

I have changed the tests.