4.0.6 Release

What's Changed

• add again multi_json as dependency by @strehle in #97

Deprecate multi_json

Background: multi_json is a dependency to other projects like uaac. cf-uaa-lib added this again - to not break existing other projects.
The removal of it will be done in several steps, means uaac first and then we can remove it again from here.
If other projects, using cf-uaa-lib, does not use multi_json in its own dependency list, then they are now called to
add this dependency on their list, because we will remove it from here again, but with some delay.

Full Changelog: v4.0.5...v4.0.6