Resolve "Add dashboard and data source provisioning for Grafana"

See merge request she/spesb!5

Add top-level package for Java implementation

Closes #6

See merge request she/spesb!3

Add the spesb prefix to all self implemented java packages of the
project. Because this changes the fully qualified class name of
the main classes the build.gradle files need to adopt to this.

Gradle + CI improvements

Closes #7

See merge request she/spesb!2

Enables the execution of the code quality tools in the subprojects
and configures them in a central place.