Refactor uiGridController to move refresh and other methods to grid

All unit tests pass.  Need to modify buildStyles to not take $scope,
I couldn't find any styleComputations that actually used it, and it
appeared that all had access to uiGridCtrl, which is the same thing
that the scope would have provided.  Some risk there.

I was unable to register the public api, I suspect that is because
the api doesn't exist without a callback, so I needed to write it
as a onRegisterApi, but that's not imperative to this current
refactor.

I've written no new unit tests as yet, although clearly they're
possible with a lot of functions moved to Grid.js.  I don't know
what most of them do to unit test them well.
Merge pull request #1516 from PaulL1/refactor_gridctrl

Refactor uiGridController to move refresh and other methods to grid