S allius/issue205 (#207)

* Add SolarmanEmu class

* Forward a device ind to establish the EMU connection

* Move SolarmanEmu class into a dedicated file

* Add cloud connection counter

* Send inverter data in emulator mode

* Improve emulator mode

- parse more values from MQTT register
- differ between inverter and logger serial no

* Add some unit tests for SolarmanEmu class

* Send seconds since last sync in data packets

* Increase test coverage

app/tests/test_modbus_tcp.py

@@ -52,6 +52,10 @@ def config_conn(test_hostname, test_port):
                             'proxy_node_id': 'test_1',
                             'proxy_unique_id': ''
                         },
+                        'solarman':{
+                            'host': 'access1.solarmanpv.com',
+                            'port': 10000
+                        },
                         'inverters':{
                             'allow_all': True,
                             "R170000000000001":{
@@ -65,7 +69,8 @@ def config_conn(test_hostname, test_port):
                                 'sensor_list': 0x2b0,
                                 'client_mode':{
                                     'host': '192.168.0.1', 
-                                    'port': 8899
+                                    'port': 8899,
+                                    'forward': True
                                 }  
                             }
                         }