Directories in import-dirs can't have spaces

[gerdemb]

split(" ") means directories can't have spaces.

fava/src/fava/core/fava_options.py

Line 213 in 3b687b0

setattr(options, key, tuple(value.strip().split(" ")))

[yagebu]

Yeah, probably would have been better to make that an option import-dir (that can be given multiple times). A PR adding that would be welcome.