Determine how to handle database transactions

[scottgonzalez]

Since each module is loaded once per app, and a single database connection is shared across all requests, transactions won't work.

[scottgonzalez]

Use connection pooling and pass the database reference as a property on the callback. The callbacks can be treated as option hashes for the method.

There should still be a single shared connection for the app which is used if no connection is passed with the callback.