Suppress output clutter in `trash` command

Previously, the `trash` command would print out path information of the
items it was deleting. This was unrelated to the verbose log messages
`trash` would print when using the '-v' option, and cluttered the
screen with long, AppleScript-style paths to the item in the ~/.Trash
directory. For example, when trashing '~/Desktop/delme', `trash` would
print:
    folder delme of item .Trash of folder mtorok of folder Users of
startup disk

This update suppresses the above messages by redirecting the output the
`osascript` command to delete the file to `/dev/null`.

Again, this should not change any of the intentional messages `trash`
prints, either in normal operations, or in verbose mode.