feature(ismailia): custom traceur options

Here is my changes to allow custom traceur options

I don't know if this verbose _karma conf_ syntax suits you.

```js
coverageReporter: {
  instrumenter: {
    '**/*.js': 'ismailia'
  },
  instrumenterOptions: {
    ismailia: {
      traceur: {
        options: {
          modules: 'instantiate'
        }
      }
    }
  }
}
```


Closes #1