subproblem inference working in dry and submit modes, added dry_run a…

[jakubczakon]

added config processing to inference experiment dir path if user doesn't specify it
refactored user interaction with dry_run to dry_train and dry_eval

[kamil-kaczmarek]

1. dry_train, dry_run: If we do it in whales, we should also do it in fashion mnist.

2. Maybe cloud_mode should be renamed to use_neptune_cloud

3. Is dev_mode used in any place?

@jakubczakon @buus2 What do you think?

[jakubczakon]

1. dry_train dry_eval is just an adapter on top of dry_run and it should work with both.
2. agreed
3. not sure, it is more for us

[buus2]

@kamil-kaczmarek
ad 1) Agree, we should be consistent.
ad 2) Agree.
ad 3) I don't know what it is for.