Added Eq and Ord instances for LocalTime.

I couldn't get the test suite to build (circular dependencies), else I would
have verified my instances against the tests. `cabal build` works, so I figure I
couldn't have completely ruined it.

The `Eq` instance is a standard `deriving` clause. The `Ord` instance compares
the output of `zonedTimeToUTC`, using `UTCTime`'s `Ord` instance.