Fixes for reclass diff and README:

Change-Id: Id7b8aa425cd7e4317ba8f2e1e640bb515392c7d1
Related-PROD: PROD-28199
diff --git a/cfg_checker/modules/reclass/comparer.py b/cfg_checker/modules/reclass/comparer.py
index 5ef2ca5..b0b7b37 100644
--- a/cfg_checker/modules/reclass/comparer.py
+++ b/cfg_checker/modules/reclass/comparer.py
@@ -57,7 +57,7 @@
         try:
             _size = 0
             with open(fname, 'r') as f:
-                _yaml = yaml.load(f)
+                _yaml = yaml.load(f, Loader=yaml.FullLoader)
                 _size = f.tell()
             # TODO: do smth with the data
             if not _yaml: