Use ! instead of , as sed delimiter in grubby-bls script
    
    The script uses sed to modify the options field in the BLS entries, but it
    is using a ',' character as the sed delimiter. It's total valid to have a
    kernel command line parameter that contains that character, for example:
    
    $ grubby --add-kernel=/boot/vmlinuz --args="console=ttyS0,115200n81" \
      --initrd=/boot/initrd.img --make-default --title=install
    sed: -e expression #1, char 42: unknown option to `s'
    
    Fix this by using a different delimiter that won't be present in a cmdline.
    
    Resolves: rhbz#1634744
    
    Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>