WIP Rework hash formats and add JSON format

[HarlemSquirrel]

Closes #70

Test object

{ a: 'cheese', 'a' => 'burger', 1 => 'fries',  1.0 => 'version', count: 33, time: Time.now, nothing: nil, list: [1, 'a', :sym, Time.now, nil], nested_hash: { hi: 'there' } }

[HarlemSquirrel]

Should we also support the JSON format for arrays? I guess the only thing it would do is convert symbols to strings inside the array which doesn't seem particularly helpful but also feels a bit incomplete without it if we're doing that in hashes.