Update rake to latest.
Report which keys were found.
Use the configured redis connection string for this spec.
Include the db number in the redis url.
Make event specs more consistent.

These have been failing intermittently for me because they had race conditions.
My solution:

- Use a shared context to manage killing the thread at the end of every test to ensure a clean thread state.
- Use a stdlib Queue to synchronize between threads; this is far better then `thread.join(0.01)`.