Fixed logging statements that would break with parameters containing '%'

Here's a minor fix for logging statements that use the pattern

```python
logger.info('message: %s' % parameter)
```

instead of the proper

```python
logger.info('message: %s', parameter)
```

The first will break as soon `parameter` contains a `%` character because the expanded message is passed to `logger.info()` which expects a parameter for every `%`. Furthermore the first approach wastes a little CPU time in cases where the message is not logged (as it is expanded in any case).