Replace gtk mainloop with glib mainloop
Replace gtk mainloop with glib mainloop

This is because Travis CI runs headless and importing gtk fails

advancedtelematic/aktualizr,advancedtelematic/sota_client_cpp,advancedtelematic/sota_client_cpp,advancedtelematic/aktualizr,advancedtelematic/aktualizr,advancedtelematic/aktualizr