Add option to 'beautify' JSON output

[bartkessels]

Add option that will lay out the JSON in a more readable way.
So when you get JSON output like this

[{'pk': 1,'name':'obj1'},{'pk':2','name':'obj2'}]

Another view should show it like this:

[
    {
        'pk': 1, 
        'name': 'obj1'
    },
    {
        'pk': 2',
        'name': 'obj2'
    }
]

[bartkessels]

Added in 91e64f3