removed the rspec deprecation.

Author: Ping Yu

spec/omniauth/strategies/ldap_spec.rb

@@ -49,7 +49,7 @@ class MyLdapProvider < OmniAuth::Strategies::LDAP; end
 
   describe 'post /auth/ldap/callback' do
     before(:each) do
-      @adaptor = mock(OmniAuth::LDAP::Adaptor, {:uid => 'ping'})
+      @adaptor = double(OmniAuth::LDAP::Adaptor, {:uid => 'ping'})
       OmniAuth::LDAP::Adaptor.stub(:new).and_return(@adaptor)
     end