FEATURE: Import and export watched word (#12444)

Find & Replace and Autotag watched words were not completely exported
and import did not work with these either. This commit changes the
input and output format to CSV, which allows for a secondary column.

This change is backwards compatible because a CSV file with only one
column has one value per line.

app/models/watched_word.rb

@@ -46,6 +46,10 @@ class WatchedWord < ActiveRecord::Base
     w
   end
 
+  def self.has_replacement?(action)
+    action == :replace || action == :tag
+  end
+
   def action_key=(arg)
     self.action = self.class.actions[arg.to_sym]
   end