Allow redacting on subdirs

[naglepuff]

Fix #170

Adds a new flag (-r or --recursive).

If this flag is provided to the imagedephi run command, then redaction will be performed on sub directories of the input directory. Additionally, the directory structure will be duplicated in the output directory.

[manthey]

When you have --skip-rename turned on, it creates the directory structure (at least one deep) from the source, but the redacted files are not in those subdirectories.

[naglepuff]

When you have --skip-rename turned on, it creates the directory structure (at least one deep) from the source, but the redacted files are not in those subdirectories.

I forgot to update the parent directory of the output file when --skip-rename is used. I fixed that with 71119f8.

I also updated the test to make sure this interaction doesn't break in the future with 231f38c.