wp-cli/wp-cli — pull request #724 by scribu (2013-08-27 20:23:50+00:00)
Title: Show usage when no parameters are passed

For commands that support a variable number of arguments (see #229), we should show the usage if 0 parameters are passed.

For example, `rm` accepts 1 or more filenames, but shows the usage when 0 are passed:

```
$ rm
usage: rm [-f | -i] [-dPRrvW] file ...
unlink file
```