Allow to pass any arguments to z

**before**
```bash
$ z -l
12         /Users/Jean/Dropbox
12         /Users/Jean/work

$ z -h
12         /Users/Jean/Dropbox
12         /Users/Jean/work

$ z work
/Users/Jean/work
```

**after**
```bash
$ z -l
12         /Users/Jean/Dropbox
12         /Users/Jean/work

$ z -h
z [-chlrtx] args

$ z work
/Users/Jean/work
```