run' returns an internal type JSON

So I was working with RethinkDB and noticed that `run' :: ... -> IO [JSON]`, which I did not enjoy since `JSON` is an internal type probably used to define instances for. Therefore this pull request changes the type to `run :: ... -> IO [Value]`, which is the real Data.Aeson format.

I bumped into this problem using the Data.Aeson.Bson and Data.Aeson-Bson packages.

I also could not compile the code initially without declaring the type of the integer 0 in line 329 ReQL.hs to Double, so I included that fix here as well.