Fixed no border style

Author: botzill

pydocx/openxml/wordprocessing/border_properties.py

@@ -88,6 +88,11 @@ def __eq__(self, other):
     def __ne__(self, other):
         return not self == other
 
+    def __nonzero__(self):
+        if self.style and self.style in ['nil', 'none']:
+            return False
+        return True
+
 
 class TopBorder(BaseBorder):
     XML_TAG = 'top'