add deprecation warning for `.restore` with object

http://edgeguides.rubyonrails.org/4_2_release_notes.html#active-record-d
eprecations
> Deprecated passing Active Record objects to .find or .exists?. Call
id on the objects first.
Commits in Rails:
https://github.com/rails/rails/commit/d92ae6ccca3bcfd73546d612efaea01127
0bd270
https://github.com/rails/rails/commit/d35f0033c7dec2b8d8b52058fb8db495d4
9596f7
https://github.com/rails/rails/commit/c0609dd0f0f0de604ac1ffeffdf5e3e0e7
356b35

lib/paranoia.rb

@@ -34,6 +34,11 @@ module Paranoia
     alias :deleted :only_deleted
 
     def restore(id, opts = {})
+      if ActiveRecord::Base === id
+        id = id.id
+        ActiveSupport::Deprecation.warn("You are passing an instance of ActiveRecord::Base to `restore`. " \
+                                        "Please pass the id of the object by calling `.id`")
+      end
       Array(id).flatten.map { |one_id| only_deleted.find(one_id).restore!(opts) }
     end
   end