… startup. Let's see what comes next.

- Documented that 4.2.0 should be used, if one is still using Spring Boot 1
- Spring Boot acutator got a big API rework in Spring Boot 2 so a lot of adaptions were neccessary here:
-- Endpoints are not exposed via HTTP by default any more, has to be configured explicitly => documented
-- Endpoint code is now technology independent and works out of the box with HTTP and JMX => removed the MvcEndpoint
-- Because the endpoint id is automagically used in http paths and config property names and some parts of springs property handly code doesn't support underscores, we had to switch to dashes
- The new spring boot version automatically collects *all* FlywayCallback Beans and adds them to the main Flyway instance. Since we want to isolate our flyway config, we had to make sure that our callbacks have a different class name.
- The Spring Boot Flyway AutoConfiguration can be disabled. In this case no FlywayProperties will exist leading to an NPE in FlywayMigrator => Fixed
- There seems to be no need any more to wrap the Actuator config in a @ManagementContextConfiguration
- Added a seperate test module that uses the k8s way to configure access tokens. It can later be copy'n'pasted to test multiple permutation of optional dependencies
- Deleted the deprecated Snapshot event provider, so that we don't carry deprecated interfaces into a new major release

…o nicely and gives us 16 Major Releases time before the Spring Boot 1.x release train overtakes the Spring Boot 2 one

…ot creation

…back methods

…alled

…alled