Fix 404 for license

## Summary

When try to read the license of the lessons from the home page of bootcamps we got 404 error.

## How to reproduce

1. Go to the home page of any [future bootcamp](http://software-carpentry.org/bootcamps/) (e.g. [Stanford University](http://arokem.github.io/2014-01-27-Stanford/), [University of Miami](http://jennybc.github.io/2014-01-27-miami/)).
2. Go to the end of the page.
3. Click on "License" icon.

**Warning**: some http server are case-insensitive but look like github.io isn't.

## Reason

The file is `LICENSE.html` and not `license.html`.

## Solution

Fix the file name.