Revisit SWDB 2019 logic in SDK

[aamster]

AllenSDK contains logic for SWDB from 2019: https://github.com/AllenInstitute/AllenSDK/tree/master/allensdk/brain_observatory/behavior/swdb

This code is broken by #2109 .

Consult with Marina as to whether SWDB 2019 logic can be removed from AllenSDK. If so, remove swdb folder in AllenSDK. If not, update modules under swdb folder so that it works.