converting draft7 schema to draft4

[DSuveges]

$ python schema_converter.py --help

usage: schema_converter.py [-h] -i DRAFT7FILE -o DRAFT4FILE

This script converts json schema written in draft7 to draft4.

optional arguments:
  -h, --help            show this help message and exit
  -i DRAFT7FILE, --draft7File DRAFT7FILE
                        Draft-7 compatible json schema filename
  -o DRAFT4FILE, --draft4File DRAFT4FILE
                        Draft-4 compatible json schema filename