Day 2: Sample .gitignore is not quite there.

[ramanshah]

There are some files starting with ._ that need to be ignored, too. Dry-run again, and make sure that the sample gitignore is ready to go. This will allow more time to help students while they make their .gitignore files.

[ramanshah]

Argh, these files seem to be aggressively hidden from the user when you use OS X. That must be why I ran into the issues developing intermediate_git on a Mac and then, e.g., teaching it on my Linux box.

Maybe the way to do this, instead, is to rebuild sample.tgz on a non-Mac machine so that the sample_ignore.gitignore is correct cross-platform.