Fix various rubocop issues.

app/helpers/application_helper.rb

@@ -121,7 +121,7 @@ module ApplicationHelper
     link_to text, wiki_page_path(title), class: "wiki-link", **options
   end
 
-  def link_to_wikis(*wiki_titles, last_word_connector: ", or", **options)
+  def link_to_wikis(*wiki_titles, **options)
     links = wiki_titles.map do |title|
       link_to_wiki title.tr("_", " "), title
     end
@@ -245,7 +245,7 @@ module ApplicationHelper
 
   def data_attributes_for(record, prefix, attributes)
     attributes.map do |attr|
-      if attr.kind_of?(Array)
+      if attr.is_a?(Array)
         name = attr.map {|sym| sym.to_s.dasherize.delete("?")}.join('-')
         value = record
         attr.each do |sym|
@@ -261,7 +261,7 @@ module ApplicationHelper
       if value.nil?
         value = "null"
       end
-      if prefix.length == 0
+      if prefix.blank?
         [:"#{name}", value]
       else
         [:"#{prefix}-#{name}", value]