Update type of cents_usd response fields

[pcothenet]

What

• Update order.price_cents_usd and order.patch_fee_cents_usd from string to integer

Why

• An integer value is more natural and directly usable by a consumer of the API

Notes

• This version can be released even before the API update since the javascript type conversion is pretty friendly. With the current API version it coerces the string nicely to integer.

SDK Release Checklist

• Have you added an integration test for the changes?
• Have you built the package locally and made queries against it successfully?
• Did you update the changelog?
• Did you bump the package version?
• For breaking changes, did you plan for the release of the new SDK versions and deploy the API to production?