Added focusNode from SHACLValidator to Schemarama SHACL validator results

[RinkeHoekstra]

This adds a node entry to the results returned by the Schemarama SHACL validator (as is described in the readme)

This fixes #48

[google-cla[bot]]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

[danbri]

Hi Rinke! Thanks for this :)

We need to be careful around the opensource licensing in this repo, hence all the CLA messages above. Are you (or employer) in a position to sign a CLA? Happy to help...