Thingsboard-gateway

Minor release for ThingsBoard IoT gateway.

Contains hotfix for docker image.

All changes are the same like in [release 3.0](https://github.com/thingsboard/thingsboard-gateway/releases/tag/3.0).

**Major release of ThingsBoard IoT gateway.**

In this release:

**Features**:

- [_Service_] GRPC API - ThingsBoard IoT gateway will start GRPC server and listen for client connections, clients can work as a connectors. Using this feature you can create your own connectors on any programming language.
- [_Modbus Connector_] Refactored Modbus Connector. Added ability to use it as a Modbus slave and Modbus master device. Improved downlink converter.
- [_Service_] Added ability to handle device removing/renaming on Thingsboard (Works with ThingsBoard 3.3.3 or above).
- [_OPC-UA Connector_] Added service RPC methods get and set for nodes on OPC-UA server.
- [_BLE Connector_] Remastered. Changed library for connecting and processing.
- [_SQLite Storage_] Improvements and added additional configuration parameters.
- [_Configuration wizard_] Added additional configuration parameters.

**Fixes**:
- [_Service_] Fix for reconnecting on sending big message.
- [_Service_] Fixed high CPU usage by connectors.
- [_Service_] Changed logic for persistent device saving, to keep device type.
- [_REST Connector_] Fixed aiohttp loop error.

**Gateway:**

- Fixed reconnection Gateway to ThingsBoard bug
- Added minPackSendDelayMS to config file
- Fixed certificate loading
- Fixed remote logging feature
- Fix for RPC calls to connectors. Thanks mjbernet3

**MQTT Connector:**

- Added JSONPath parsing to RPC `valueExpression` config section
- Added `attributeRequests` config section
- Added `retain` flag for attributeUpdates, attributeRequests
- Added opportunity to combine values in attributes, telemetry and serverSideRpc config sections

**Modbus Connector:**

Added configuration parameters:

- retries - Count of retries if polling was failed (default 3)
- retryOnError - Retry to get data if server returns an error (default true)
- retryOnInvalid - Retry to get data if server returns invalid data (default true)

**REST Connector:**

- Added SSL Support
- Added JSONPath parsing to RPC `valueExpression` config section
- Added opportunity to combine values in attributes, telemetry and serverSideRpc config sections

**BACNet Connector:**

- General improvements

**Request Connector:**

- General improvements
- Added JSONPath parsing to RPC `valueExpression` config section
- Added opportunity to combine values in attributes, telemetry and serverSideRpc config sections

**ODBC Connector:**

- Bugs fixed (adding timestamp to telemetry)

**FTP Connector:**

- Added opportunity to combine values in attributes, telemetry config section for JSON files

Minor release of ThingsBoard IoT gateway.
This release contains:

1. Fix for checking message size to send to ThingsBoard. Added parameter "maxPayloadSizebytes" for messages from the gateway to ThingsBoard, default value is **4096** bytes.
2. Added new storage type - SQLite.
3. Fixes for minor bugs in connectors.
4. Added multi-threading processing in connectors.
5. Minimal version of Python changed to 3.7

ThingsBoard IoT gateway minor release contains:
- FTP connector - allows to connect to FTP servers, find files by paths and process data from them.

Includes fixes and improvements for:

- MQTT connector;
- Modbus Connector;
- Gateway service fixes and improvements;

ThingsBoard IoT gateway minor release, includes fixes and improvements for:

- MQTT connector;
- Modbus Connector;
- Request Connector;
- ODBC Connector;
- TB Gateway service fixes and improvements;