added test to verify that advisory_lock_exists? was added to the ActiveRecord classes
added test to verify that advisory_lock_exists? was added to the ActiveRecord classes

ClosureTree/with_advisory_lock,mceachen/with_advisory_lock,mceachen/with_advisory_lock,ishumilova/with_advisory_lock,BraneLabs/with_advisory_lock,BraneLabs/with_advisory_lock,ishumilova/with_advisory_lock