TST: Remove SubtractedImages; test old and new Images API.
TST: Remove SubtractedImages; test old and new Images API.

ericdill/datamuxer,danielballan/datamuxer,danielballan/dataportal,NSLS-II/dataportal,ericdill/datamuxer,danielballan/dataportal,danielballan/datamuxer,ericdill/databroker,ericdill/databroker,NSLS-II/dataportal,NSLS-II/datamuxer