Automatic population of data and processing version into L1 / L2 datasets

[DavidMcCann-NOC]

The data version and processing version needs to be parsed and stored in any saved data from the L1-to-L2 processing chain. This potentially could use a class to write the attributes, but will also require:

• Data / SAR focussing versions to be standardised and decided upon
• The code to have a release (and therefore a version number)
• A connection between github version and the code to write the attributes automatically