Replace json4s by other json SerDe

[cerveada]

Since json4s seems to be causing compatibility issues between different versions of Spark and shading, it seems to be difficult (see #667) it is worth considering to replace it by different library.

Ideal features of the library would be:

• Support for Scala 2.11, 2.12, 2.13
• Stable - Ideally a library that keeps each major release in a different package, described here
• Automatic mapping of case classes to json

Some candidates:

https://github.com/spray/spray-json no automapping

https://github.com/rallyhealth/weePickle no automapping

[wajda]

ef674f44290f4670da88e0037b694995b2dd3c4f - A quick attempt to replace a shaded Json4s with a shaded Jackson + Scala module