TransactionClassifier: report when parser cache is disabled

@wladekb, please review

```
TransactionTrace: notification: ["onAttributeChange","parser_cache_used","parser_cache_disabled"]
TransactionTrace: notification: ["onTypeChange","page\/main\/view\/oasis\/parser_disabled"]

TransactionTrace: notification: ["onAttributeChange","parser_cache_used",false]
TransactionTrace: notification: ["onTypeChange","page\/main\/view\/oasis\/parser"]

TransactionTrace: notification: ["onTypeChange","page\/main\/view\/oasis"]
```