Improved debuggability by passing through log messages by default.

Added support for `flags: []` passthrough in configuration. This allows you to add a debug configuration to your karma config:

```javascript
      customLaunchers: {
         'PhantomJS-debug': {
            base: 'PhantomJS',
            options: {
               windowName: 'PhantomJS (debug)',
            },
            flags: ['--remote-debugger-port=9000']
         }
      }
```