Try to fix ConcurrentModificationException

Exception in thread "Thread-12"
java.util.ConcurrentModificationException
at java.util.ArrayList$Itr.checkForComodification(Unknown Source)
at java.util.ArrayList$Itr.next(Unknown Source)
at
cloudsync.client.FileSysPerformer$PerformThread.run(FileSysPerformer.java:135)