Integrate context-testing into develop

See merge request teraflow-h2020/controller!8

Add database/Factory.py missing file

See merge request teraflow-h2020/controller!6

Initial release of context service

See merge request teraflow-h2020/controller!5

Move database to common folder, since it will be used also by device service, and implement very minor changes.

Merge Request Feat/gitlab ci into develop

See merge request teraflow-h2020/controller!2

Requirements.txt added to .gitignore file

Merge request for monitoring branch to develop

See merge request teraflow-h2020/controller!1

Monitoring manifest for K8s added

- monitoring/test_monitoring.py: provides a basic testing skeleton
- monitoring/requirements.in/.txt: updated with pytest
- monitoring/genproto.py: added instructions to import generated Python modules using "from . import ..." instead of "import ..."; otherwise, pytest and other possible modules doing imports might complain.
- monitoring/monitoring_server.py: packed start_server and stop_server functionaity to simplify test definition, minor formattings, bug resolutions and improvements in package import.
- monitoring/monitoring_client.py: minor formattings, bug resolutions, and improvements in package import.