put --args [args] after the file argument on OS X
put --args [args] after the file argument on OS X

For the OSX open command, the --args [arg ...] arguments come after the file argument, not before:

````
NAME
     open -- open files and directories

SYNOPSIS
     open [-e] [-t] [-f] [-F] [-W] [-R] [-n] [-g] [-h] [-b bundle_identifier]
          [-a application] file ... [--args arg1 ...]
````

This shows itself as a bug in chrome in the case where chrome is running, but without any active windows.

Closes #29

sindresorhus/opn,sindresorhus/opn