Fix a bug in the *.spec files and also apply the following major changes:

- Add support for adding the base folder to PATH.
- Only display one pop up window at a time in order to avoid confusion.
- Add automatic updates feature:
	- Windows and Linux versions will be shipped with an updater program used to
	  update both Artemis and the updater itself.
	- MacOs versions will not have the updater. Instead the user will be asked
	  to download the new software version (if present) via browser.

src/audio_player.py

@@ -2,8 +2,8 @@ import os
 from pygame import mixer
 from PyQt5.QtCore import QTimer, pyqtSlot, QObject
 
-from constants import Constants
 import qtawesome as qta
+from constants import Constants
 
 
 class AudioPlayer(QObject):
@@ -127,7 +127,6 @@ class AudioPlayer(QObject):
         """Set the current audio sample."""
         self._reset_audio_widget()
         full_name = os.path.join(
-            Constants.DATA_FOLDER,
             Constants.AUDIO_FOLDER,
             fname + '.ogg'
         )