dfxml_tool.py: Add optional provenance

Signed-off-by: Alex Nelson <a.nelson@prometheuscomputing.com>
dfxml_tool: Clean file-not-found error output

Signed-off-by: Alex Nelson <a.nelson@prometheuscomputing.com>
Add unit tests for Python ('make check')

Signed-off-by: Alex Nelson <a.nelson@prometheuscomputing.com>
Python: Update changelog

Signed-off-by: Alex Nelson <a.nelson@prometheuscomputing.com>