Format numbers in locale as well (not all languages use the same)

Done according to
https://developer.android.com/training/basics/supporting-devices/languages#FormatNumbers

briar-android/src/main/java/org/briarproject/briar/android/contact/ContactListItemViewHolder.java

@@ -10,6 +10,8 @@ import org.briarproject.briar.R;
 import org.briarproject.briar.android.contact.BaseContactListAdapter.OnContactClickListener;
 import org.briarproject.briar.android.util.UiUtils;
 
+import java.util.Locale;
+
 import javax.annotation.Nullable;
 
 import static android.support.v4.view.ViewCompat.setTransitionName;
@@ -36,7 +38,7 @@ class ContactListItemViewHolder extends ContactItemViewHolder<ContactListItem> {
 		// unread count
 		int unreadCount = item.getUnreadCount();
 		if (unreadCount > 0) {
-			unread.setText(String.valueOf(unreadCount));
+			unread.setText(String.format(Locale.getDefault(), "%d", unreadCount));
 			unread.setVisibility(View.VISIBLE);
 		} else {
 			unread.setVisibility(View.INVISIBLE);

briar-android/src/main/java/org/briarproject/briar/android/threaded/ThreadPostViewHolder.java

@@ -8,6 +8,8 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.threaded.ThreadItemAdapter.ThreadItemListener;
 
+import java.util.Locale;
+
 import static android.view.View.GONE;
 import static android.view.View.VISIBLE;
 
@@ -45,7 +47,8 @@ public class ThreadPostViewHolder<I extends ThreadItem>
 		}
 		if (item.getLevel() > 5) {
 			lvlText.setVisibility(VISIBLE);
-			lvlText.setText(String.valueOf(item.getLevel()));
+			lvlText.setText(
+					String.format(Locale.getDefault(), "%d", item.getLevel()));
 		} else {
 			lvlText.setVisibility(GONE);
 		}

briar-android/src/main/java/org/briarproject/briar/android/view/TextAvatarView.java

@@ -12,6 +12,8 @@ import android.widget.TextView;
 
 import org.briarproject.briar.R;
 
+import java.util.Locale;
+
 import javax.annotation.Nullable;
 
 import de.hdodenhof.circleimageview.CircleImageView;
@@ -44,7 +46,7 @@ public class TextAvatarView extends FrameLayout {
 
 	public void setUnreadCount(int count) {
 		if (count > 0) {
-			badge.setText(String.valueOf(count));
+			badge.setText(String.format(Locale.getDefault(), "%d", count));
 			badge.setVisibility(VISIBLE);
 		} else {
 			badge.setVisibility(INVISIBLE);

briar-android/src/main/java/org/briarproject/briar/android/view/UnreadMessageButton.java

@@ -12,6 +12,8 @@ import android.widget.TextView;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
 
+import java.util.Locale;
+
 import javax.annotation.Nullable;
 
 @UiThread
@@ -69,7 +71,7 @@ public class UnreadMessageButton extends FrameLayout {
 		} else {
 			fab.show();
 			unread.setVisibility(VISIBLE);
-			unread.setText(String.valueOf(count));
+			unread.setText(String.format(Locale.getDefault(), "%d", count));
 		}
 	}