Handle latest MAT comments in population logic views

### Story ###
- https://www.pivotaltracker.com/story/show/75374788

### Notes ###
- updated Gemfile to point to latest <code>bonnie_bundler</code>, <code>health-data-standards</code> (bonnie_master branch), and <code>simplexml_parser</code>
- renders comments for preconditions (including root preconditions within populations)
- styled to match generated MAT human readable with italicized comments

### Screenshot ###
![screen shot 2014-07-22 at 9 24 50 am](https://cloud.githubusercontent.com/assets/456952/3658473/f1aa3b74-11a3-11e4-9d81-ca733be74c8f.png)