Add support for ssl-protocol specification in engines

The ability to ingore-ssl-errors was not enough for my particular use case.  Adding the option to specify the ssl-protocol allowed the underlying phantomjs execution to process my host using the 'any' option.

Is it now possible to use this configuration:

```
grunt.initConfig( {
    phantomas: {
        yourSite : {
            options : {
                options   : {
                    'ssl-protocol': 'any',
                    'ignore-ssl-errors': true
                },
            }
        }
    }
} );
```