Add spray json support

[Alexey U.]

Hi,

I'm using akka-http with SprayJsonSupport, it would be awesome to add spray json support out of box.

[PJ Fanning]

https://github.com/theiterators/kebs appears to support enumeratum with spray-json

[sviat stoliarenko]

I working on macros library for spray and will add support of enumeratum

[Ferenc Tóth]

@bc-tayvs do you have any news about that project?