GitLab

This huge commit adds the following features:

- Change default timeout to 5 sec (to be updated soon)
- Don't send TTP information in contract file, but during start signal
- Platform: load and save TTP data from a local file
  New flags: --addr and --ttps
- Platform ttp command: automatically save ttp data in the local file
  (addr and certificate hash are the only values needed by the platform
  and the clients)
- Update integration tests to integrate TTP

- Add mgdb entities to handle resolution protocol
- Add unit tests

- Factorizes code between promises and signatures
- Add a cooldown before starting the first round
- Add demonstrator trace in integration tests