zsh 5.0.5

Bump ZSH to 5.0.5 as both download hosts (fossils.org and zsh.org) have removed the tar files for 5.0.4.

On a related note, it may be a good idea to switch back to or add the Debian FTP (as listed on the Debian sid page: http://packages.debian.org/sid/zsh) for downloading ZSH as it retains previous versions of ZSH while the current download hosts seem to drop the old versions as soon as a new version is released.