Batching similar (pair/exchange/interval) strategies duplicates candles in the database

[eristoddle]

This may have been caused by my refactoring of the original Titan code. I don't have 100% handle on python PubSub, Threads and Queues and may have broken something. So there were at least 4 tickers running. The fix is to go to using Celery to replace most of this functionality. But a prevention would be a better handling of duplicate candles in the database similar to the way I save strategy data. But the duplicate ticker problem also becomes an issue with exchange api limits.