Pass --grep to protractor

[joeheyming]

If I have:
grunt.registerTask('test', ['clean', 'protractor']);

If I run:
grunt test --grep 'my test'

I'd like that to pass --grep to the protractor command. (seen here: angular/protractor#164 (comment))

I looked at the protractor runner source and did not see this

Currently I'm using fit() and fdescribe(), I guess that is good enough. But if I want to instruct non-javascript devs how to run my integration tests, they won't want to edit javascript.