Isis special pixels (#577)

* Single clean commit for parallel ground

* Adds capability to use a redis write cache to improve performance

* simplify config via redis setup

* FIxes regression in measures

* Initial work on async watchers

* Fixes serialization when a relationship can't be loaded from a detached instance.

* Fixes regression in images

* Removes debug prints

* Fixes backref - need to be single sided

* dtype checking for reads

* Fices missed merge issues

* added np2isis dtype code

Co-authored-by: jay <jlaura@usgs.gov>
Co-authored-by: Jay <jlaura@asu.edu>