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### Issue description
The datadir field on the debug window displays incorrectly if the profile folder name is accented.

### How to reproduce
1. Create a profile with accented profile folder name (àèìòùáéíóú)
2. Run bitcoin core with the default datadir
3. Go to the debug window and look at the datadir field

### Expected behaviour
The datadir folder path should display correctly.

### Actual behaviour
Accented characters display as a unknown character question mark.

### Screenshots
![Debug Window](https://cloud.githubusercontent.com/assets/11365204/20029647/41dee90e-a352-11e6-8784-e5a48798d62e.png)


### Confirmed affected versions
The bug has been tested on the following implementations:

- v0.13.1 from source cross-compiled for Windows x64 on a Ubuntu 14.04 enviroment
- 0.13.0 official Windows x64 binary

### Additional debug info
Copying and pasting the text into a program that is known to support accented characters (Such as Notepad++) still displays unknown character symbols.
QString certFile = QString::fromStdString(GetArg("-rootcertificates", "-system-"));
    
    if (certFile.isEmpty()) {
        qDebug() << QString("PaymentServer::%1: Payment request authentication via X.509 certificates disabled.").arg(__func__);
        return;
    }
    QList<QSslCertificate> certList;
    if (certFile != "-system-") {
            qDebug() << QString("PaymentServer::%1: Using \"%2\" as trusted root certificate.").arg(__func__).arg(certFile);
        certList = QSslCertificate::fromPath(certFile);
        
        QSslSocket::setDefaultCaCertificates(certList);
    } else
        certList = QSslSocket::systemCaCertificates();
    int nRootCerts = 0;
    const QDateTime currentTime = QDateTime::currentDateTime();
    Q_FOREACH (const QSslCertificate& cert, certList) {
        
        if (cert.isNull())
            continue;
        
        if (currentTime < cert.effectiveDate() || currentTime > cert.expiryDate()) {
            ReportInvalidCertificate(cert);
            continue;
        }
#if QT_VERSION >= 0x050000
        
        if (cert.isBlacklisted()) {