ESON to support lists of enum

Updated the proposal provider to show a list of enum literals
![02](https://cloud.githubusercontent.com/assets/3328139/2642233/b23e3440-bf05-11e3-86ee-6b7d2838bae5.png)
![01](https://cloud.githubusercontent.com/assets/3328139/2642234/b23e8fbc-bf05-11e3-82ef-523b16a498f3.png)