Remove dependency from views_json

[tanius]

The Edgesense Drupal module still depends on views_json, but practically this is no longer needed because the functionality is now provided by a dependency from views_datasource. Also, views_json can no longer be installed in the usual ways, since it got discontinued in favor of views_datasource.

To simplify the installation process, the views_json dependency should be removed. However, I don't know for sure if my analysis above is fully correct, so please double check what has to be done.