[Qt] Rework of payment request UI (mainly for insecure pr)

- this shows insecure (unsecured) payment requests in a new yellowish
  colored UI (based on the secure payment request UI) instead of our
  normal payment UI
- allows us to receive paymentACK messages for insecure payment requests
- allows us to handle expirations for insecure payment request
- changed walletmodel, so that all types of payment requests don't touch
  the addressbook

src/qt/sendcoinsdialog.cpp

@@ -102,7 +102,7 @@ void SendCoinsDialog::on_sendButton_clicked()
 
         QString recipientElement;
 
-        if (rcp.authenticatedMerchant.isEmpty())
+        if (!rcp.paymentRequest.IsInitialized()) // normal payment
         {
             if(rcp.label.length() > 0) // label with address
             {
@@ -114,10 +114,14 @@ void SendCoinsDialog::on_sendButton_clicked()
                 recipientElement = tr("%1 to %2").arg(amount, address);
             }
         }
-        else // just merchant
+        else if(!rcp.authenticatedMerchant.isEmpty()) // secure payment request
         {
             recipientElement = tr("%1 to %2").arg(amount, GUIUtil::HtmlEscape(rcp.authenticatedMerchant));
         }
+        else // insecure payment request
+        {
+            recipientElement = tr("%1 to %2").arg(amount, address);
+        }
 
         formatted.append(recipientElement);
     }
@@ -313,7 +317,7 @@ void SendCoinsDialog::pasteEntry(const SendCoinsRecipient &rv)
 bool SendCoinsDialog::handlePaymentRequest(const SendCoinsRecipient &rv)
 {
     QString strSendCoins = tr("Send Coins");
-    if (!rv.authenticatedMerchant.isEmpty()) {
+    if (rv.paymentRequest.IsInitialized()) {
         // Expired payment request?
         const payments::PaymentDetails& details = rv.paymentRequest.getDetails();
         if (details.has_expires() && (int64)details.expires() < GetTime())