Turn off mccabe errors in python linting

McCabe errors for complexity of functions do not always require a fix. Suggestion is to ignore mccabe errors surfaced by pylama. This can be accomplished by using the following config.

[pylama]
ignore = C901

[pylama:pycodestyle]
max_line_length = 88
ignore = E203,E231,W503,E501

[pylama:pylint]
max_line_length = 88

Added in !443 (merged)