Record git repo, hash and run command in generated XML

[aekiss]

It would be good to include the git repo, hash and run command like this as an XML comment in the output from the two scripts in data_stream_xml_generation

[dougiesquire]

@ezhilsabareesh8, the tools to get this metadata have now been moved into a scripts_common.py file in the base dir. Would you be able to use these to add the necessary provenance metadata in the data_stream_xml_generation scripts? You can find an example of how to use them in generate_mesh.py

[dougiesquire]

Note you can add comments to xml:

<!--
  This is a 
  multiline comment
-->

So you could add a comment with the metadata at the top of the file

[dougiesquire]

Closed by #15