* Create Leaderboard component. Update Top Selling Products to use it.
* Use date picker values in Top Selling Products.
* Convert top selling products tests into leaderboard tests
* Updates per feedback.
* Skipping failing test for now.
* Hook up taxes to endpoint
* Hook up tax stats endpoint
* Add default tax stat totals for empty results
* Create subtotals from intervals in API
* Change orders to orders_count to keep consistent naming
* Use X-WP-Total header to set the total number of items in tables
* Improve naming
* Improve tests
* Make getReportItems() return a 'data' property by default
* Make getSummary prop behavior more clear