Fix ArduinoJson (Using ARDUINOJSON_VERSION_MAJOR)

[Ruandv]

This is relates to the ArduinoJson 5 / 6 changes.
I took what @bigjohnson did in a502456 and just added a #define UseJsonV6 option that can be commented out if you want to use ArduinoJsonV5.
Tested on ArduinoJson V 5.13 and ArduinoJson V 6.13 (Latest as at 14/01/2020)

This also links to #654 and #812

• update examples to be compatible with future arduinojson library
• Maybe add support in the example in question for both versioons somehow?
• Can also Close Two examples ArduinoJson 6 compatibility changes #945

[bigjohnson]

Perfect, but I think is better automate it replacing
#ifdef UseJsonV6
with
#if ARDUINOJSON_VERSION_MAJOR >= 6

[Ruandv]

Ok good suggestion. Thank you I didn't know there is a way to do that. Will update it soon

[tablatronix]

I should have rebased this.. Should be ok

[userweb2018]

Can you check the sketch, there is not "}" in void setup!
It is correct?
I am having problems with ondemand config portal WithFSParameters using a push button.

[tablatronix]

Compiles for me

[userweb2018]

For me too, but this is strange....
It is not working perfectly everytime!
In which way can I use it with ondemand with pushbuttom and parameters?