fix dropping gnu info dir files
Merge pull request #29 from niksula/fix_infodir_drop

fix dropping gnu info dir files
Don't mask failures in verbose mode

When using the -p option, we echo command output to the screen by
piping to tee. This masks the exit status of the initial command,
leading us to not fail when we should. We now return the status of
the first command.
use $SUDO for sudo
Merge pull request #32 from niksula/use_sudo_variable

use $SUDO for sudo