Feature request: provide a way to skip option parsing

[nfischer]

Commands like grep() provide option parsing, which is awesome. But it would be great if I could tell shelljs when to not do option parsing.

In the shell, sometimes I want to actually grep for -v in a file, instead of using it as an option.

In the shell:

$ grep -- -v file.txt

Proposed shelljs feature:

shell.grep('--', '-v', 'file.txt');