Code refactor, support multiple gateways and non-SAML authentication (#9)

* Code refactor

* Update README.md

GPClient/normalloginwindow.cpp

@@ -0,0 +1,62 @@
+#include "normalloginwindow.h"
+#include "ui_normalloginwindow.h"
+
+#include <QCloseEvent>
+
+NormalLoginWindow::NormalLoginWindow(QWidget *parent) :
+    QDialog(parent),
+    ui(new Ui::NormalLoginWindow)
+{
+    ui->setupUi(this);
+    setFixedSize(width(), height());
+}
+
+NormalLoginWindow::~NormalLoginWindow()
+{
+    delete ui;
+}
+
+void NormalLoginWindow::setAuthMessage(QString message)
+{
+    ui->authMessage->setText(message);
+}
+
+void NormalLoginWindow::setUsernameLabel(QString label)
+{
+    ui->username->setPlaceholderText(label);
+}
+
+void NormalLoginWindow::setPasswordLabel(QString label)
+{
+    ui->password->setPlaceholderText(label);
+}
+
+void NormalLoginWindow::setPortalAddress(QString portal)
+{
+    ui->portalAddress->setText(portal);
+}
+
+void NormalLoginWindow::setProcessing(bool isProcessing)
+{
+    ui->username->setReadOnly(isProcessing);
+    ui->password->setReadOnly(isProcessing);
+    ui->loginButton->setDisabled(isProcessing);
+}
+
+void NormalLoginWindow::on_loginButton_clicked()
+{
+    const QString username = ui->username->text().trimmed();
+    const QString password = ui->password->text().trimmed();
+
+    if (username.isEmpty() || password.isEmpty()) {
+        return;
+    }
+
+    emit performLogin(username, password);
+}
+
+void NormalLoginWindow::closeEvent(QCloseEvent *event)
+{
+    event->accept();
+    reject();
+}