Json support for basic types

[yaitskov]

Hi,

I want to configure aws services in my app. Configuration is described in JSON.

e.g. 'Aws.LogLevel' and 'Aws.Core.Protocol' doesn't implement ToJSON/GHC.Generics.Generic.

I spot that Aws.Core.Protocol implements Typeable and Aeson was supporting auto marshaling for Typeable types, but it looks like it doesn't work anymore.

Now I had to rewrap all these types into newtypes.