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

* Code refactor

* Update README.md

GPClient/gphelper.h

@@ -0,0 +1,43 @@
+#ifndef GPHELPER_H
+#define GPHELPER_H
+
+#include "samlloginwindow.h"
+#include "gpgateway.h"
+
+#include <QObject>
+#include <QNetworkAccessManager>
+#include <QNetworkRequest>
+#include <QNetworkReply>
+#include <QUrlQuery>
+#include <QSettings>
+
+
+const QString UA = "PAN GlobalProtect";
+
+namespace gpclient {
+    namespace helper {
+        extern QNetworkAccessManager *networkManager;
+
+        QNetworkReply* createRequest(QString url, QByteArray params = nullptr);
+
+        SAMLLoginWindow *samlLogin(QString samlMethod, QString samlRequest, QString preloginUrl);
+
+        GPGateway& filterPreferredGateway(QList<GPGateway> &gateways, QString ruleName);
+
+        QUrlQuery parseGatewayResponse(const QByteArray& xml);
+
+        void openMessageBox(const QString& message, const QString& informativeText = "");
+
+        void moveCenter(QWidget *widget);
+
+        namespace settings {
+
+            extern QSettings *_settings;
+
+            QVariant get(const QString &key, const QVariant &defaultValue = QVariant());
+            void save(const QString &key, const QVariant &value);
+        }
+    }
+}
+
+#endif // GPHELPER_H