zshrc: drop trailing space in grep and ls _options

zshrc: drop trailing space in grep and ls _options

If an alias ends with a space char the shell will expand the next
word as an alias as well, even if it's not a global alias.

Bug demonstration:

| % which "grep"
| grep: aliased to grep --color=auto
| % which "ls"
| ls: aliased to ls -b -CF --color=auto
| % grep ls  ~/.gitconfig
| grep: F: invalid context length argument

Thanks: Frank Terbeck <ft@grml.org> for the bugfix
Acked-by: Frank Terbeck <ft@grml.org>