Determine a better method for exposing external task registration and task implementation

[vkottler]

It's not practical for every workflow task to make it into this package and get full unit testing.

right now the "load tasks/conf.py" mechanism works fine, but it's still hard to maintain something like https://github.com/vkottler/config/tree/master/python/mklocal

Would there be a better way to do this?