Add testSchedulingGarbageCollectionOnAnotherThread
Add testSchedulingGarbageCollectionOnAnotherThread

* Tests that scheduling works on a thread other than
main
chrisbtreats/SPTPersistentCache,spotify/SPTPersistentCache,iOSCowboy/SPTPersistentCache,FootballAddicts/SPTPersistentCache,spotify/SPTPersistentCache,chrisbtreats/SPTPersistentCache,FootballAddicts/SPTPersistentCache,chrisbtreats/SPTPersistentCache,FootballAddicts/SPTPersistentCache,FootballAddicts/SPTPersistentCache,chrisbtreats/SPTPersistentCache,iOSCowboy/SPTPersistentCache,iOSCowboy/SPTPersistentCache,spotify/SPTPersistentCache