Put helper methods into System.Directory.Generic.
Fixed bug w.r.t. filenames

The UUID filenames were shown too often, resulting in extra quote marks,
which caused the saving of the files to fail.
Added quoteArg

Calling crawlers with spaces in their name caused problems because the
name was split by runCommand in CLI.hs:224. I added a quoting funciton
which re-adds quotations marks.
Closes #48.

The check for `all isSpace` was inverted.