MemoryQueue TODOs
Base class for Queue implementation
Custom error - NotImplemented
Subclass of QueueBase now
Better comments
wasAlreadyEnqueued + enqueuUrl takes object instead of url, processor name and optional data
Added exist() placeholder + put() parameters swapped
Merge commit 'ecc6f624d639e1bb18214760c3a756990f729326' into sreality-scraper