Thingsboard-gateway

Minor release which includes bug fixes and integration with Sigfox Backend.

Minor release with the following MQTT extension improvements:
- Configure devices using Thingsboard Attributes feature.
- Control devices using Thingsboard RPC feature.

Initial Thingsboard IoT Gateway release provides following features:
- **OPC-UA** extension to collect data from devices that are connected to OPC-UA servers.
- **MQTT** extension to collect data that is published to external MQTT brokers.
- **Persistence** of collected data to guarantee data delivery in case of network and hardware failures.
- **Automatic reconnect** to Thingsboard cluster.
- Simple yet powerful **mapping** of incoming data and messages **to unified format**.