Deprecate euroix-list.json

[jpaussa]

Need to work out if we can generate this dynamically rather than having a static file. I am not familiar with the data here so I am not sure where the source of truth is for it.

[afenioux]

The official list is at https://github.com/euro-ix/json-schemas/blob/master/README.md
it may (or may not fully) be up to date. Some IXP (like DE-CIX for example) have restricted access to their members list in JSON. So even if we populate dynamically the list we also need to keep the possibility for users to add manually JSON files of members lists or to give the URLs.

[cooperlees]

Yeah - this is causing errors now when trying to refresh:
http://pastebin.com/Z2FXpiUi