Trace and Background steps should use SpecReduceOperation

[cshanahan1]

@eteq explained to me that the purpose of defining SpecReduceOperation was for users not comfortable with objects to be able to call the operations like functions and use them sequentially to construct pipelines (maybe he can elaborate on this more?). The extraction classes use SpecReduceOperation as their base class, but the trace and background steps don't. There should also be an explanation of this workflow in the documentation, once it's implemented for all operations.