### Describe the issue
Warning messages are not displayed when running bitcoin-qt 0.14.2 and 0.14.99 with -disablewallet.
It might be better to always display them.

E.g. on MainNet the "This is a pre-release test build - use at your own risk - do not use for mining or merchant applications" is lost
![image](https://user-images.githubusercontent.com/3296421/29109760-853e5394-7ce4-11e7-8f05-bfcd66ada471.png)
![image](https://user-images.githubusercontent.com/3296421/29109806-adf6e67a-7ce4-11e7-8564-8883c44656ad.png)

On TestNet also the "Warning: unknown new rules activated (versionbit 28)" is missed
![image](https://user-images.githubusercontent.com/3296421/29110269-6b24b79e-7ce6-11e7-91e7-823227eaa200.png)
![image](https://user-images.githubusercontent.com/3296421/29110035-9142cf34-7ce5-11e7-8faf-264e805cdaf4.png)

{
    this->walletModel = model;
    if(model && model->getOptionsModel())
    {
        
        filter.reset(new TransactionFilterProxy());
        filter->setSourceModel(model->getTransactionTableModel());
        filter->setLimit(NUM_ITEMS);
        filter->setDynamicSortFilter(true);
        filter->setSortRole(Qt::EditRole);
        filter->setShowInactive(false);
        filter->sort(TransactionTableModel::Date, Qt::DescendingOrder);
        ui->listTransactions->setModel(filter.get());
        ui->listTransactions->setModelColumn(TransactionTableModel::ToAddress);
        
        interfaces::Wallet& wallet = model->wallet();
        interfaces::WalletBalances balances = wallet.getBalances();
        setBalance(balances);
        connect(model, &WalletModel::balanceChanged, this, &OverviewPage::setBalance);
        connect(model->getOptionsModel(), &OptionsModel::displayUnitChanged, this, &OverviewPage::updateDisplayUnit);
        updateWatchOnlyLabels(wallet.haveWatchOnly() && !model->privateKeysDisabled());
        connect(model, &WalletModel::notifyWatchonlyChanged, [this](bool showWatchOnly) {
            updateWatchOnlyLabels(showWatchOnly && !walletModel->privateKeysDisabled());
        });
    }
    
    updateDisplayUnit();
}
void OverviewPage::updateDisplayUnit()