Restructure for better usability

gui/about/about.py

@@ -0,0 +1,13 @@
+from kivy.uix.screenmanager import Screen
+from kivy.lang import Builder
+import webbrowser
+
+from gui.popups.popups import SingleRowPopup
+
+
+class AboutScreen(Screen):
+    def report_issue(self):
+        SingleRowPopup().open("Opened your web-browser")
+        webbrowser.open('https://github.com/janishutz/BiogasControllerApp/issues', new=2)
+
+Builder.load_file('./gui/about/about.kv')