JDBC connectors should be deployed to the Servlet Container separatly.
The dependency is now only used for the embedded development Servlet
container and has been upgraded to version 8.0.x.

* Using Spring Boot Dependencies BOM
* Set up Logback for logging
* Updated dependencies and plugins
* Removed unused dependencies
* Bumped source compatibility to version 1.8

This feature seems to be overkill for the LMS Connector's use case and
has never been used in production.

We remove it because:
* it increased creates code maintenance overhead
* the integrated database increases the the memory footprint

:connector-client and :connector-service depend on :connector-model:xjc
task.

This prevents generated pom file to set all dependencies as runtime scope.