Disable Style/IfUnlessModifier

This rule creates an issue where resolving the rule to appease haml-lint
then triggers another rule in rubocop, so it's being disable in the
haml-lint configuration file

Author: KPobeeNorris

.haml-lint.yml

@@ -4,3 +4,7 @@ linters:
 
   ClassesBeforeIds:
     EnforcedStyle: "id"
+
+  RuboCop:
+    ignored_cops:
+      - Style/IfUnlessModifier