fix haml linter declaration

This is necessary in order to boot delayed_job -_-
Without this, it attempts to inherit a missing class

lib/linters/application_name_linter.rb

@@ -1,46 +1,48 @@
-module HamlLint
-  class Linter::ApplicationNameLinter < Linter
-    include LinterRegistry
+if defined?(HamlLint)
+  module HamlLint
+    class Linter::ApplicationNameLinter < Linter
+      include LinterRegistry
 
-    FORBIDDEN = 'demarches-simplifiees.fr'
-    REPLACEMENT = "APPLICATION_NAME"
-    MSG = 'Hardcoding %s is forbidden, use %s instead'
+      FORBIDDEN = 'demarches-simplifiees.fr'
+      REPLACEMENT = "APPLICATION_NAME"
+      MSG = 'Hardcoding %s is forbidden, use %s instead'
 
-    def visit_tag(node)
-      check(node)
-    end
-
-    def visit_script(node)
-      check(node)
-    end
-
-    def visit_silent_script(node)
-      check(node)
-    end
-
-    def visit_plain(node)
-      check(node)
-    end
-
-    def visit_comment(node)
-      check(node)
-    end
-
-    def visit_haml_comment(node)
-      check(node)
-    end
-
-    def check(node)
-      line = line_text_for_node(node)
-      if line.downcase.include?(FORBIDDEN)
-        record_lint(node, format(MSG, FORBIDDEN, REPLACEMENT))
+      def visit_tag(node)
+        check(node)
       end
-    end
 
-    private
+      def visit_script(node)
+        check(node)
+      end
 
-    def line_text_for_node(node)
-      document.source_lines[node.line - 1]
+      def visit_silent_script(node)
+        check(node)
+      end
+
+      def visit_plain(node)
+        check(node)
+      end
+
+      def visit_comment(node)
+        check(node)
+      end
+
+      def visit_haml_comment(node)
+        check(node)
+      end
+
+      def check(node)
+        line = line_text_for_node(node)
+        if line.downcase.include?(FORBIDDEN)
+          record_lint(node, format(MSG, FORBIDDEN, REPLACEMENT))
+        end
+      end
+
+      private
+
+      def line_text_for_node(node)
+        document.source_lines[node.line - 1]
+      end
     end
   end
 end