Remove VCR cucumber tags

We'll only use VCR to wrap HTTP backed repositories
Refactor Repository cache keys
Introduce a VCR repository for acceptance tests

We'll use our VCR repository to wrap HTTP backed repositories at
runtime to provide us with fast, deterministic repositories when we
perform our acceptance tests.
Record acceptance test repositories using VCR
Record cassettes against production API
Record article repository
Remove cassettes from article step definitions
Remove cassettes from action plan definitions
Remove cassettes from searching definitions
Remove cassettes from Category and SEO definitions
Merge branch 'vcr-usage' into breadcrumbs-performance
Use fixtures for article acceptance tests
Add acceptance tests for article breadcrumbs