python-json-schema-validator: new package

[Thomas: convert to the Python package infrastructure, fix license
informations.]
[Peter: there is no LICENSE.txt]
Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>