Signed-off-by: gkatsikas <gkatsikas@ubitech.eu>

Implementing refinements in the webui: dividing forms for selecting the context and uploading json files in the home page; listing and detailing existing services.

- Added upload of descriptors file
- Added scripts to generate descriptor files
- Arranged minor script details
- Minor bug fixing

- 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.