train_base_command() is border line too complex according to flake8

[SamuelLarkin]

While debugging for #419, I had to add some debugging code, not that much and when I tried to commit my changes, flake8 was complaining that train_base_command() was too complex.
We should consider refactoring that function.

flake8...................................................................Failed
- hook id: flake8
- exit code: 1

everyvoice/base_cli/helpers.py:147:1: C901 'train_base_command' is too complex (42)