Code review comment for ~jcastets/cloud-init:scaleway-datasource

Some things, and some content inline:
 * We'll need some unit tests for this. Otherwise it is at increased risk of being inadvertently broken.
 * We will need to add knowledge of the datasource to tools/ds-identify (without that your datasource will only ever be considered if it is a single entry in the configured list)
 * we really, *REALLY* want a positive non-network identification. Without such a thing, we can't enable the datasource by default, meaning Ubuntu or other images that would work elsewhere wont work on your platform.

Also, give a nicer commit message:
  Summary
  <blank line>
  More information
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  <blank line>
  LP: #XXXXXXX