Nested keys

[cl3wis]

Allow a list of strings to be passed to JsonPydexer.index() in the first positional argument.
EG ["personInfo", "contact", "phone"] would access "555-555-5555":

{
    personInfo: {
        contact: {
            phone: "555-555-5555"
        }
    }
}

• Add or identify test data
• Write the tests
• Pass the tests