Refactor in the mechanism of saving and exporting

- new imgur upload interface.
- rework for a better code structure. It still needs another change separating the Controller from the code dedicated to export data to the system.
- created the concept of "worker", component used to do some work based on a screenshot.

src/utils/screengrabber.cpp

@@ -0,0 +1,44 @@
+// Copyright 2017 Alejandro Sirgo Rica
+//
+// This file is part of Flameshot.
+//
+//     Flameshot is free software: you can redistribute it and/or modify
+//     it under the terms of the GNU General Public License as published by
+//     the Free Software Foundation, either version 3 of the License, or
+//     (at your option) any later version.
+//
+//     Flameshot is distributed in the hope that it will be useful,
+//     but WITHOUT ANY WARRANTY; without even the implied warranty of
+//     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//     GNU General Public License for more details.
+//
+//     You should have received a copy of the GNU General Public License
+//     along with Flameshot.  If not, see <http://www.gnu.org/licenses/>.
+
+#include "screengrabber.h"
+#include <QPixmap>
+#include <QScreen>
+#include <QGuiApplication>
+#include <QApplication>
+#include <QDesktopWidget>
+
+ScreenGrabber::ScreenGrabber(QObject *parent) : QObject(parent) {
+
+}
+
+QPixmap ScreenGrabber::grabEntireDesktop() {
+    QRect geometry;
+    for (QScreen *const screen : QGuiApplication::screens()) {
+        geometry = geometry.united(screen->geometry());
+    }
+
+    QPixmap p(QApplication::primaryScreen()->grabWindow(
+                  QApplication::desktop()->winId(),
+                  geometry.x(),
+                  geometry.y(),
+                  geometry.width(),
+                  geometry.height())
+              );
+    p.setDevicePixelRatio(QApplication::desktop()->devicePixelRatio());
+    return p;
+}