Stop scan before connecting to Medisana

Fixes #353 (hopefully)

android_app/app/src/main/java/com/health/openscale/core/bluetooth/BluetoothCommunication.java

@@ -227,6 +227,10 @@ public abstract class BluetoothCommunication {
      */
     protected void onBluetoothDataChange(BluetoothGatt bluetoothGatt, BluetoothGattCharacteristic gattCharacteristic) {}
 
+    protected boolean doScanWhileConnecting() {
+        return true;
+    }
+
     /**
      * Set the Bluetooth machine state to a specific state.
      *
@@ -455,6 +459,10 @@ public abstract class BluetoothCommunication {
     private void connectGatt(BluetoothDevice device) {
         Timber.i("Connecting to [%s] (driver: %s)", device.getAddress(), driverName());
 
+        if (!doScanWhileConnecting()) {
+            stopLeScan();
+        }
+
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
             bluetoothGatt = device.connectGatt(
                     context, false, gattCallback, BluetoothDevice.TRANSPORT_LE);

android_app/app/src/main/java/com/health/openscale/core/bluetooth/BluetoothMedisanaBS44x.java

@@ -47,6 +47,12 @@ public class BluetoothMedisanaBS44x extends BluetoothCommunication {
         return "Medisana BS44x";
     }
 
+    @Override
+    protected boolean doScanWhileConnecting() {
+        // Medisana seems to have problem connecting if scan is running (see #278 and #353)
+        return false;
+    }
+
     @Override
     protected boolean nextInitCmd(int stateNr) {
         return false;