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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.
{
    bool fVerified = (requestSize <= BIP70_MAX_PAYMENTREQUEST_SIZE);
    if (!fVerified) {
        qWarning() << QString("PaymentServer::%1: Payment request too large (%2 bytes, allowed %3 bytes).")
            .arg(__func__)
            .arg(requestSize)
            .arg(BIP70_MAX_PAYMENTREQUEST_SIZE);
    }
    return fVerified;
}
bool PaymentServer::verifyAmount(const CAmount& requestAmount)
{
    bool fVerified = MoneyRange(requestAmount);
    if (!fVerified) {
        qWarning() << QString("PaymentServer::%1: Payment request amount out of allowed range (%2, allowed 0 - %3).")
            .arg(__func__)
            .arg(requestAmount)
            .arg(MAX_MONEY);
    }
    return fVerified;
}