Update for python3 to import the right StringIO

Author: chander

shape_engine/__init__.py

@@ -95,9 +95,12 @@
                                  DateTimeField: ogr.OFTDateTime}
 
 try:
-    from cStringIO import StringIO
-except ImportError:
-    from StringIO import StringIO
+    from io import StringIO
+    except ImportError:
+        try:
+            from cStringIO import StringIO  
+        except ImportError:
+            from StringIO import StringIO
 
 DEFAULT_FIELD_NAME_LENGTH = 10
 
@@ -111,4 +114,4 @@
 
 ENGINE_MAPPINGS = {ENGINE_FIONA: ENGINE_FIONA_MAPPING,
                    ENGINE_NATIVE: ENGINE_NATIVE_MAPPING,
-                   ENGINE_CTYPES: ENGINE_CTYPES_MAPPING}
+                   ENGINE_CTYPES: ENGINE_CTYPES_MAPPING}