fail to create (new, duplicate) resource(s) if "Overwrite existing resources" is not checked and resource with same name already exists

[hanecak]

Do not create (new, duplicate) resource(s) if "Overwrite existing resources" is not checked and resource with same name already exists, fail with an error instead.

Note: uv-l-filesToCkan ends with following error in such case:

Execution failed because: Resource data-catalog-stats-current.csv already exists at destinationeu.unifiedviews.dpu.DPUException: Resource data-catalog-stats-current.csv already exists at destination at eu.unifiedviews.helpers.dpu.context.ContextUtils.dpuException(ContextUtils.java:226)

Similar should be done in ul-l-relationalToCKAN.

We need that to fix OpenDataNode/open-data-node#223 .