PasteUpload task changed to use 0x0.st's protocol

- Modified PasteUpload task to upload the log file to 0x0.st and other
  services with the same protocol.

- Modified Paste settings UI to allow the user to select a custom paste
  URL, simplified the settings page code.

launcher/ui/pages/global/PastePage.h

@@ -54,9 +54,6 @@ private:
     void loadSettings();
     void applySettings();
 
-private slots:
-    void textEdited(const QString &text);
-
 private:
     Ui::PastePage *ui;
 };