remove use of DataKinds from Tuple and fix kind error

The use of `DataKinds` gives some issues in GHC 7.4 when using `cabal repl`, in addition to other odd compiler failures.  Because of this, they are removed (and plain `*` and `(->)` kinds and kind constructors are used, instead).  Also, a build failure occurs when using GHC 7.4 in `Control.Lens.At` due to `Proxy :: * -> *`, when `Proxy :: (* -> *) -> *` is expected (and succeeds in > 7.4 due to use of `PolyKinds` in `tagged`).