Detect "(DAPI|Nuclei)" as auxiliary image

[joshmoore]

Discussed during the 2019 SpaceJam in Seattle. Longer-term, the model may be adapted to add metadata to a channel in the main tensor.

[joshmoore]

see spacetx/starfish#1317

I am using spacetx writer but it is not clear how to add auxiliary images like NUCLEI that must be separated from primary ones