Thingsboard-gateway

Fixes:
- Fix for 255 Resolved issue with expressions in the converter.

Minor release with the following improvements.

**Main features:**
* Implemented remote configuration feature;
* Added support of JSON Path expressions in converters;
* Added ability to implement RPC calls to connectors through general service;
* Rewritten OPC-UA Connector search;
* disableSubscriptions - if true the gateway disables subscriptions and activates read values in nodes only on scanning/re-scanning.
* subCheckPeriodInMillis - interval in milliseconds to check information in nodes from subscription.

**Additional features:**

* Improvements for collecting statistic about processed events;
* Improvements for remote logging feature;

**Bug fixes:**

* [OPC-UA Connector] Fix loading type definitions on the OPC-UA server 244;
* [OPC-UA Connector] Fix for loading methods of the device;
* [OPC-UA Connector] Fix for 249;
* [MQTT Uplink Converter] Fix for digits interpretation;
* [Modbus Uplink Converter] Fix for float digits interpretation;

NOTE: This release has a critical bug which was fixed in v2.2.1.
Use of version 2.1.1 is discouraged.

This is a minor release that contains:
- OPC-UA extension fix for Securtiy Type 'None'

v2.0.4-draft1
This is a release containing:
1. Fixed reconnecting to TB when TB server restarts
2. Improved logging
3. Other minor fixes

Open-source Python IoT Gateway.

Release notes:

- Some fixes

This is the release of the ThingsBoard Gateway. We are keen to improve our gateway, so within next releases you should expect new features and improvements.
The very basic data flow is as follows:
Incoming data goes to Connector — Connector forwards data to converter(s) and receives ThingsBoard suitable data — Connector sends the data to Persistent storage — ThingsBoard Gateway service delivers the data to ThingsBoard IoT Platform.
The Persistent storage (Event storage) is used to temporary store the telemetry, attributes and other events produced by Connectors until they are delivered to ThingsBoard. There are 2 types of storage — memory (RAM) and file (HDD).

**Implemented connectors:**

- **MQTT** - You can connect to external MQTT brokers.
**Supported features:**

Subscription to topics on the broker for collection incoming data.
Publishing to topics on the broker after processing RPC requests from the ThingsBoard.
Subscription to RPC response topic on the broker.
Handling shared attribute update requests from the ThingsBoard.


- **Modbus** - You can connect to external Modbus servers/clients.
**Supported features:**

Reading data from registers.
Processing data from devices as telemetry and attributes on ThingsBoard.
RTU over TCP/UDP.
Serial RTU/ASCII client.
Processing shared attribute update request from ThingsBoard.
Opportunity for call functions on device/server on receiving RPC request from ThingsBoard.


- **OPC-UA** - You can connect to external OPC-UA servers.
**Supported features:**

Recursive scan over nodes in server.
Processing data from devices as telemetry and attributes on ThingsBoard.
Processing RPC requests from ThingsBoard.
Processing shared attribute update request from ThingsBoard.
Recursive search over path in the server.


- **Bluetooth Low Energy** - You can connect to different BLE devices.
**Supported features:**

Processing data from devices as telemetry and attributes on ThingsBoard.
Read/Write/Notify characteristics methods are supported.
Processing shared attribute update request from ThingsBoard.
Processing RPC requests from ThingsBoard.


- **Requests** - You can add any url's and send (GET, POST, etc.) HTTP requests
**Supported features:**

Processing data from external endpoints of API and interpretation it as attributes/telemetry on ThingsBoard.
POST, PUT, DELETE, HEAD, PATCH, OPTIONS methods.
Added custom bytes/bits converter to process data from response.
Processing shared attribute update requests from ThingsBoard.
Processing RPC requests from ThingsBoard.