minor changes in TelemetryFrontend

src/telemetry/backend/tests/testTelemetryBackend.py

src/telemetry/database/TelemetryModel.py

src/telemetry/database/managementDB.py

.../frontend/service/TelemetryFrontendServiceServicerImpl.py

src/telemetry/frontend/tests/Messages.py

src/telemetry/frontend/tests/test_frontend.py