change formatting for modactions on alias/implication update + add mod action for tag batch changes

app/logical/moderator/tag_batch_change.rb

@@ -12,6 +12,8 @@ module Moderator
 
       CurrentUser.without_safe_mode do
         CurrentUser.scoped(updater, updater_ip_addr) do
+          ModAction.create(:description => "processed mass update: #{antecedent} -> #{consequent}")
+
           ::Post.tag_match(antecedent).where("true /* Moderator::TagBatchChange#perform */").find_each do |post|
             post.reload
             tags = (post.tag_array - normalized_antecedent + normalized_consequent).join(" ")