- initial skeleton (not functional)

Device:
- Implemented Driver API with some special resources to enable retrieving endpoints from devices, interfaces, and network instances.
- Implemented special resource_keys (_connect/*) to enable AddDevice to obtain settings used to connect to remote devices (address, port, username, password, etc.)
- Implemented Emulated Driver (only for testing)
- Implemented OpenConfig Driver (missing to implement monitoring; templates for Infinera devices to be tested with other device vendors)
- Minor bugs and code improvements
- Improved test unit to enable easy testing of vendor devices and keep credentials secret.

- added missing proto files in genproto.sh
- created .gitignore files to prevent sharing device credentials and data
- improved MonitoringLoops class with one thread per driver for data collection, a unique aggregation queue and one single thread for data export to monitoring
- added GetResource method to Driver API
- improved DriverFactory to select the driver that better fits with filter fields in terms of number of correspondences in filter fields. Drivers with some mismatch filter are discarded.
- implemented proper initialization and connection of drivers to real devices
- started to implement OpenConfig driver with support for Infinera Packet Routers