Giving clearer messages when validating data with ShEx.
2.1. Before: we always showed a success message whenever the validation took place normally, even if some nodes were non-conformant.
2.2. After: we have additional messages in case the validation goes right but some nodes are not conformant.
2.2. After: we have additional messages in case the validation goes right but some nodes are not conformant.![image](https://user-images.githubusercontent.com/35763574/100356231-3ce2ff80-2ff3-11eb-9ea4-e7587c59f607.png)