I have been using the json.tool quite often by running `cat my-file.json | python -m json.tool` or (`:%! python -m json.tool` in vim) to pretty print the json file, but I would like to customize the indentation level to 2 indentation spaces instead of default of 4. Unfortunately, `json.tool` is hard-coded to use 4 spaces for indentation, so I am filing this issue to propose this change.