Validate if inserted books already exist with different data
Merge remote-tracking branch 'origin' into feature/WB-127

Conflicts:
	worblehat-web/src/main/java/de/codecentric/psd/worblehat/web/controller/InsertBookController.java
Merge remote-tracking branch 'origin' into feature/WB-127
Merge remote-tracking branch 'origin' into feature/WB-127