Add an App Store customer-review page as a test fixture #142

Goal

Add a recorded itunes.apple.com/{cc}/rss/customerreviews/page=1/id={app}/sortby=mostrecent/xml response to the test fixtures, with author names scrubbed.

Scope

• Fixture includes the leading app-metadata entry (no im:rating) and several review entries
• Author names replaced with placeholders
• Used by the im: and double-<content> tests

Acceptance

• Fixture is in the test bundle and loaded by at least one test

Spec

Needed by brightdigit/what-are-next (docs/SPEC.md §4.4).

Tracked in

• brightdigit/what-are-next#12