Use API and load multiple entities at once in registration_cron

[levelos]

In 3c30089, any reason not to use registration_load_multiple or at least EntityFieldQuery? Regardless, we can load all the entities at once using registration_load or just entity_load rather than entity_load_single each time through the loop.

[alexellison]

Fixed by commit 6f38beaad5e13d37cce4db6eba59f79ed19ae725