Add immediate parameter to BLE connection commands. (#1137)

* Add immediate parameter to BLE connection commands.

When sending a command to read/write a characteristic on a BLE server this adds a new parameter to cause the action to be
performed immediately. This will stop the scan in progress to perform the actions queued.

Example use:
```
mosquitto_pub -t home/OpenMQTTGateway/commands/MQTTtoBT/config -m '{
  "ble_write_address":"AA:BB:CC:DD:EE:FF",
  "ble_write_service":"cba20d00-224d-11e6-9fb8-0002a5d5c51b",
  "ble_write_char":"cba20002-224d-11e6-9fb8-0002a5d5c51b",
  "ble_write_value":"TEST",
  "value_type":"STRING",
  "ttl":4,
  "immediate":true }'
```

Stop BLE processing when immeditate command sent.

* Use a shorter connection timeout.

* Update docs.

* Remove MQTT spam for connection retrys

* Prevent crashing when the normal connection process occurs at the same time as an immediate action.

* Use a semaphore to protect BLE device vector.

main/ZgatewayBLEConnect.ino

@@ -50,14 +50,14 @@ bool zBLEConnect::writeData(BLEAction* action) {
           std::string temp = action->value.substr(i, 2);
           buf.push_back((uint8_t)strtoul(temp.c_str(), nullptr, 16));
         }
-        return pChar->writeValue((const uint8_t*)&buf[0], buf.size(), !pChar->canWrite());
+        return pChar->writeValue((const uint8_t*)&buf[0], buf.size(), !pChar->canWriteNoResponse());
       }
       case BLE_VAL_INT:
-        return pChar->writeValue(strtol(action->value.c_str(), nullptr, 0), !pChar->canWrite());
+        return pChar->writeValue(strtol(action->value.c_str(), nullptr, 0), !pChar->canWriteNoResponse());
       case BLE_VAL_FLOAT:
-        return pChar->writeValue(strtod(action->value.c_str(), nullptr), !pChar->canWrite());
+        return pChar->writeValue(strtod(action->value.c_str(), nullptr), !pChar->canWriteNoResponse());
       default:
-        return pChar->writeValue(action->value, !pChar->canWrite());
+        return pChar->writeValue(action->value, !pChar->canWriteNoResponse());
     }
   }
   return false;
@@ -82,12 +82,12 @@ bool zBLEConnect::processActions(std::vector<BLEAction>& actions) {
       if (NimBLEAddress(it.addr) == m_pClient->getPeerAddress()) {
         JsonObject BLEresult = getBTJsonObject();
         BLEresult["id"] = it.addr;
-        BLEresult["service"] = (char*)it.service.toString().c_str();
-        BLEresult["characteristic"] = (char*)it.characteristic.toString().c_str();
+        BLEresult["service"] = it.service.toString();
+        BLEresult["characteristic"] = it.characteristic.toString();
 
         if (it.write) {
           Log.trace(F("processing BLE write" CR));
-          BLEresult["write"] = it.value.c_str();
+          BLEresult["write"] = it.value;
           result = writeData(&it);
         } else {
           Log.trace(F("processing BLE read" CR));
@@ -117,9 +117,11 @@ bool zBLEConnect::processActions(std::vector<BLEAction>& actions) {
           }
         }
 
-        it.complete = true;
+        it.complete = result;
         BLEresult["success"] = result;
-        pubBT(BLEresult);
+        if (result || it.ttl <= 1) {
+          pubBT(BLEresult);
+        }
       }
     }
   }