Solve minor issue in unitary test of Context that prevented tests to finish correctly in random cases.

Common:
- added chk_attribute to type_checkers module.
- recovered run_tests_locally.sh

Compute:
- updated requirements.in
- updated Config.py
- updated RestServer
- implemented IETF-L2VPN NBI plugin
- implemented unitary tests for IETF-L2VPN NBI plugin including a Mock OSM client, and Mock Context and Service components

- Implement WIM REST API for OSM
- Implement IETFL2VPN REST API
- Implement unitary tests for OSM-Compute-Service workflow

Added L3NM-OpenConfig Service Handler

See merge request teraflow-h2020/controller!51

First functional version of Service with Service Handler for L3NM-Emulated services using Emulated Devices

See merge request teraflow-h2020/controller!50

First functional version of Service with Service Handler for L3NM-Emulated services using Emulated Devices

Final arrangements in Device monitoring

See merge request teraflow-h2020/controller!49

First functional version of Device monitoring

See merge request teraflow-h2020/controller!48

Commit for the first code freeze

See merge request teraflow-h2020/controller!46

Add first draft for TE service

See merge request teraflow-h2020/controller!47

Multiple adjustments in CI/CD pipeline and related issues.

See merge request teraflow-h2020/controller!45

Updated gRPC proto files to prevent trouble with KPI sample types in devices, also updated files related to this issue.

DLT component

See merge request teraflow-h2020/controller!43