Feature: Log to function if request.logger is a function and verbose == true

To log a SQL transaction using **node-mssql**, one typically sets ```req.verbose = true```.

However, this is hardcoded to use ```console.log()``` which is not always appropriate.
This patch allows a user-defined function to be used instead.

```coffeescript
req.verbose = true
req.logger = logger.debug
```

This assumes logger.debug is a function which takes a single argument.