Fix all trailing spaces for custom guidelines

There are several trailing spaces error raised by
custom guidelines check. Need to fix them for successful
pep8 running.

implements bp custom-guidelines

Change-Id: Ibf50208155315e75795d7b9c8a8dbe487f9046ac

tools/custom_guidelines.py

@@ -25,7 +25,7 @@ from heat.engine import support
 
 class HeatCustomGuidelines(object):
 
-    _RULES = ['resource_descriptions']
+    _RULES = ['resource_descriptions', 'trailing_spaces']
 
     def __init__(self, exclude):
         self.error_count = 0