Addresses in JSON are rendered as JSON objects containing hex strings but should be strkeys

[leighmcculloch]

What version are you using?

bda0d98

What did you do?

Use serde_json to convert values in this crate to JSON, that contain the ScVal::Address value.

What did you expect to see?

The strkey representation of the address. e.g. A... or C...

What did you see instead?

{
    "address": {
        "contract": "fc21c6967fda947c012695d185c9f78bcb97e380c6811d12f4b525f6fb54f9a0"
    }
}