Added Exoscale as Provider

[FaKod]

Exoscale is a trademark of Akenes SA, a private company founded in 2011 and headquartered in Switzerland. My company uses their cloud offers to host Kubernetes clusters.

With this PR I implemented Exoscale's DNS API as additional provider.
Let me know what you think...

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[FaKod]

Signed the CLA and changed my author email accordingly.

[greut]

@FaKod my e-mail address should be okay as well.

[njuettner]

Thank for your PR @FaKod 🙂

It would be nice to have a tutorial to get started with Exoscale.

I'll have a look at the code.

[njuettner]

Just to understand it a bit better, why do you ignore the updates? I just only see that you're looping over update changes even if you would use a logging level which is not debug?

[FaKod]

I must admit that for my use case it seems to be sufficient to only support create and delete. Is update mandatory?

[njuettner]

I'm just only asking because I never saw that someone wouldn't want to update their records. Could there people which might need it?

If you don't use it at all I'm not seeing any point looping over updates which doesn't do anything execept logging.

[FaKod]

@njuettner I've added UpdateNew, while still iterating over UpdateOld, just for logging reasons (like it is done in pdns.go)

[FaKod]

The label docs-missing means actually tutorial missing?

[njuettner]

@FaKod yes sorry for the confusion. Tutorial is missing, do you mind to add it as well and add it also in the README.md. There are already other links pointing to the provider tutorials.

[FaKod]

@njuettner for the tutorial... Which external-dns version should I refer to?

[njuettner]

v0.5.5

[njuettner]

@FaKod it's looks like the tests are failing in types.go. Could you take a look again?

[FaKod]

@njuettner Sorry... should work now

[njuettner]

/LGTM

[njuettner]

Sorry I wasn't seeing it but you have to add

- apiGroups: [""]
  resources: ["nodes"]
  verbs: ["list"]

to run external-dns with RBAC

[njuettner]

Thanks again for your PR!