Change the type of numbers presented in String using the new json types

[dabitdev]

Then numeric values coming in each response will be presented in a json numeric type. The library should be able to present this numbers using numeric native types instead of Strings. The consumer app should never convert String types to Integers, Floats or Dates.

Current json responses

when you add the new header
'merapi-output' = 'json'

this changes are already visible in dev and will be promoted in July 2nd to production.