feat(cli): support for multiCapabilities in command line

For example, this command:

    protractor protractor.config.js --multiCapabilities.0.browserName chrome --multiCapabilities.1.browserName firefox

is the equivalent of putting this in your config file:

    multiCapabilities: [{
      'browserName': 'chrome'
    }, {
      'browserName': 'firefox'
    }],

or you can do this:
    
    protractor protractor.config.js --multiCapabilities.0.browserName firefox --multiCapabilities.0.count 3


which is the equivalent of:

    multiCapabilities: [{
      browserName: firefox,
      count: 3
    }]