add set difference exercise
Putting note in index page explaining purpose.
More instructions on bootcamp home page template.
Starting to work on Git tutorial
updated exercise to make more sense, and hopefully be more interesting
Adding a note about countries to template files
Brief explanation of branching
Talking about merging in Git
Adding GitHub to tutorial
Import installation test scripts from boot-camps repo.
Fix typo.
Merge pull request #17 from douglatornell/typos

Fix typo.
Merge pull request #16 from douglatornell/setup-check

Import installation test scripts from boot-camps repo.
Fleshing out description of GitHub and adding discussion of licensing issues
Merge branch 'gh-pages' of github.com:swcarpentry/bc into gh-pages
Adding a CITATION file to the bootcamp template repository
Shortening title of Git tutorial
1. Editing and extending the lesson on testing.
2. Changing the `rectangle_area` function's name (we only need one version in the end).
3. Adding a `border` function for another example.
4. Modifying `ears` to take a `prefix` argument specifying which tests to run.
Adding link to index page
Adding link to Git tutorial