Suggestions for Improvement for the eBird 1.1 API.

• See this comment on making the regional hot spot lookup provide a filtering mechanism to show only hot spots with recent data.
• In the header for XML results, we should add a warehouseDate to indicate when the last refresh occurred on the primary warehouse from which the result is based. This will let consumers decide whether or not they should expect recent data to show up in the result or not.