Translate spaces to '_' to fix an ZFS issue. See http://forums.openmediavault.org/index.php/Thread/2972-ZFS-plugin/?postID=60611#post60611.

git-svn-id: http://svn.code.sf.net/p/openmediavault/code/trunk@1585 3c3d7b80-5828-415e-9f61-280b98178fff