Policy component's protobufs are updated based upon
the Event Condition Action (ECA) model.
Minor fixes are applied to the slice.proto in order
to compile.

Signed-off-by: Georgios Katsikas <katsikas.gp@gmail.com>

Minor fixes to correct CI/CD issues.

See merge request teraflow-h2020/controller!31

Multiple fixes to correct problems with common.database in Compute, Service and CentralizedAttackDetector.

See merge request teraflow-h2020/controller!30

- Corrections in Service to prevent errors in GitLab CI/CD pipeline.
- Minor improvements in random classes.

Merge monitoring-service to develop

See merge request teraflow-h2020/controller!28

# Conflicts:
#   .gitignore
#   .gitlab-ci.yml