Fix rubocop exception

Author: parkr

lib/jekyll-import/importers/wordpressdotcom.rb

@@ -59,7 +59,7 @@ def initialize(node)
         end
 
         def text_for(path)
-          subnode = @node.at_xpath('./' + path) || @node.at(path) || @node.children.find { |child| child.name == path }
+          subnode = @node.at_xpath("./#{path}") || @node.at(path) || @node.children.find { |child| child.name == path }
           subnode.text
         end