Adding StringIO import for Python3

Author: DasFranck

sc2reader/engine/plugins/creeptracker.py

@@ -3,14 +3,14 @@
 
 try:
     from sets import Set
-except:
+except ImportError:
     Set = set
 from PIL.Image import open as PIL_open
 from PIL.Image import ANTIALIAS
 try:
     from StringIO import StringIO
-except:
-    pass
+except ImportError:
+    from io import StringIO
 from collections import defaultdict
 from itertools import tee