fix #16: Give the app a home page

[brotskydotcom]

1. Added home page template and logic to client.
2. Added handler for home page.
3. Integrated home page handler into dispatch logic.
4. Improved logging in the handlers.
5. Improved use of redis mutex so it's always released.
6. Improved shutdown logic so redis connection is always closed and the reason for the shutdown is always logged. We wait for the mutex when shutting down so running handlers are not stopped in mid-transaction. We hold the mutex when shutting down so all other handlers are prevented from running against the database.
7. Added a signal handler to gracefully catch aborts.