Modifying default layout of bootcamp pages to give instructors and helpers more prominence.

1.  Moved list of instructors from `index.html` to `_layout/bootcamps.html` in order to put it in the header.
2.  Added a dependency in `Makefile` so that the site will rebuild when templates are changed.

Question: should the entire header well be moved into `./index.html` so that it's easier for bootcamp site authors to find and modify?  (We've found in the past that people find the `_includes` mechanism confusing.)

![screen shot 2014-06-25 at 6 45 52 am](https://cloud.githubusercontent.com/assets/911566/3384214/409472f8-fc56-11e3-83f6-6a1eef742e08.png)