Implement new functional test for I/O classification - config change

[katlapinka]

Description

1. Start cache, add core
2. Load I/O class config
3. Run I/O
4. Check statistics
5. Load different I/O class config
6. Check statistics - should be zeroed

By default data should be unclassified, so per IO class statistics should be zeroed (except IO class with unclassified rule). There will be a flag to prevent data unclassification.