Missing a lot of mappers for Short and Byte

There are few things missing in play framework:

1. `Reads[Byte]` and `Writes[Byte]`.

2. Form mappings for Short and Byte, currently we have only `number` and `longNumber`. It would be nice to also have `shortNumber` and `byteNumber` (so min and max parameters could be used in form helper for HTML5 `<input type="number">`)

3. `Formatter[Short]` and `Formatter[Byte]`.

4. (bonus) All of the above for `Enumeration`s