Replaced rm_rf function in lib.py with shutil.rmtree.

I came across a problem with icybackup when used in conjunction with django-antichaos, as antichaos creates a symlink in your app's media directory to its own media directory in its installation path.

Your components.lib.rm_rf function would follow the symlink, kill the contents of antichaos' media directory (in a virtualenv) and then fail to delete the symlink using os.rmdir() at the end of rm_rf().

Replacing components.lib.rm_rf with shutil.rmtree seemed to do the trick.