Files created in wrong locations if CDPATH environment variable is set with any values

``rcup`` creates symlinks to folders in the current folder for subfolders of folders in the dotfiles directory if the ``CDPATH`` environment variable is set. 

Originally I thought the problem was that my dotfiles folder was in the CDPATH, but I tested with CDPATH only set to equal ``.`` and experienced the same problem.

I think the solution might be to copy ``CDPATH`` environment variable's contents to a temporary variable, ``unset CDPATH``, execute the tasks, then copy the value back at the conclusion of the script. However, I'm not a shell script expert, so there might be a much better option I'm missing.