Updated Dividend and Split to be children of HistoricalPrice
Merged batches and commands
Removed old adjusted_price implementation
Converted related code to use new dividend/split model
Refactored Populate structure
Fixed snapshot_set <=> select_related
Changed from_manager to be extra invocation instead of a different constructor
Added PriceAdjustment calculation
Fixed price adjustment to generate correct values
Optimized PriceAdjustment populate