Properly sanitize mv parameters (CVE-2014-8990)

When using -rsyncssh option, some filenames
could -in addition of not syncing correctly-
crash the service and execute arbitrary commands
under the credentials of the remote user.

These issues have been assigned CVE-2014-8990

This commit fixes the incomplete and lua5.2-incompatible
sanitization performed by 18f02ad0

Signed-off-by: Sven Schwedas <sven.schwedas@tao.at>