Add absolute paths to meta sources

[lrodrin]

If we are working with a relative path, convert the input metadata sources paths to absolute paths for VRE tools executions.

So, it is needed to add a validation in:

openvre-tool-api/apps/jsonapp.py

Lines 273 to 284 in 99613be

	else:
	# Set input sources
	meta_sources_list = list()
	for input_name in input_metadata.keys():
	meta_sources_list.append(input_metadata[input_name][1].file_path)
	meta.sources = meta_sources_list
	# Set metadata
	meta.meta_data = metadata["file"].get("meta_data", None)
	results.append(_newresult(role, path, meta))