Pass empty array for a config via command line API

### Expected behavior

I want to override the `browsers` config with an empty array. I used `--browsers=[]` or `--browsers=` with no luck.
### Actual behavior

Karma ignores my arguments or complains that `[]` is not installed
### Enviroment Details

Ubuntu Linux
- Karma version (output of `karma --version`): Karma version: 0.13.22
- Relevant part of your `karma.config.js` file: test/karma.conf.js