Applying extract method to message acknowledgement
Using block for AMQP connection
Pulling subscription logic into separate class
Using method chaining in worker.rb
Using AMQP.start instead of EM specific calls
Avoiding race condition by using Channel.queue with a block
Passing channel instead of exchange to UnpublishedFilesSubscriber.new
Moving queue subscription logic to unpublished_files_subscriber
Mocing file processing logic to FileExecutor
Adding FileExecutionStatus
Adding a bit more synchronization.  This may not be necessary, but I
remember from my programing with Java that some wierd instruction
reordering can be done if a memory barrier isn't in place around state
accessed by multiple threads.  There shouldn't be a whole lot of
concurrent access going on with this data structure so the performance
hit isn't mush of a concern.
Adding revision to test_run