[v2] Cloud only version

[c-seeger]

Attlassian removed the Self-Hosted version of Jira/Confluence of their product portfolio.

The current codebase was build to support both versions, but since the API's diverge more and more a V2 refactor should be done to support only the Cloud version while keeping the Self-Hosted code in a different repository.

This clean's the code and creates a clear use case for both clients (cloud and self-hosted) without the need of mixing code snippets for compatibility reasons.

[c-seeger]

CC: @mikfreedman

[Roemer]

Atlassian still provides self-hosted versions, which are called "Data Center". They are basically just a much much much more expensive Server version but with the added benefit of being able to scale.