Run bandit from code

[buhtz]

I would like to "run" bandit from code after import bandit and collect its result (e.g. as dict or json).

I can do something similar with pycodestyle

import pycodestyle

pep = pycodestyle.Checker(file_path)
assert pep.check_all() == 0

[ericwb]

There is a feature issue opened already to suggest this change in #626