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/weatherdata.py

@@ -1,10 +1,12 @@
 import re
 from PyQt5.QtGui import QPixmap
 from PyQt5.QtCore import pyqtSlot, pyqtSignal, QObject
-from threads import (BaseDownloadThread,
-                     UpdateSpaceWeatherThread,
-                     ThreadStatus,
-                     UpdateForecastThread)
+from threads import (
+    BaseDownloadThread,
+    UpdateSpaceWeatherThread,
+    ThreadStatus,
+    UpdateForecastThread
+)
 from constants import Constants
 from switchable_label import MultiColorSwitchableLabel
 from utilities import safe_cast