extend controller.js function getDeviceInfoForMqtt (#1274)

* Add Discord channel. https://github.com/Koenkk/zigbee2mqtt.io/issues/31

* extend controller.js function getDeviceInfoForMqtt

extend controller.js with 
``
zclVersion,
appVersion,
stackVersion,
hwVersion,
swBuildId,
``

* Rework #2

Only Publish hwVersion and swBuildId as this seems to be valid as posible.
Map with default option 'unknown' to be in a good way.

* Fix tests

* Update README.md

lib/controller.js

@@ -267,7 +267,7 @@ class Controller {
 
     getDeviceInfoForMqtt(ieeeAddr) {
         const device = this.zigbee.getDevice(ieeeAddr);
-        const {type, nwkAddr, manufId, manufName, powerSource, modelId, status} = device;
+        const {type, nwkAddr, manufId, manufName, powerSource, modelId, hwVersion, swBuildId, status} = device;
         const deviceSettings = settings.getDevice(device.ieeeAddr);
 
         return {
@@ -279,6 +279,8 @@ class Controller {
             manufName,
             powerSource,
             modelId,
+            hwVersion: hwVersion ? hwVersion : 'unknown',
+            swBuildId: swBuildId ? swBuildId : 'unknown',
             status,
         };
     }