fix length on session table index

db/migrate/20170421195415_add_index_to_token_hashes_on_authie_sessions.authie.rb

@@ -1,6 +1,6 @@
 # This migration comes from authie (originally 20170421174100)
 class AddIndexToTokenHashesOnAuthieSessions < ActiveRecord::Migration
   def change
-    add_index :authie_sessions, :token_hash
+    add_index :authie_sessions, :token_hash, :length => 8
   end
 end