new file:   Solutions/session_01/box_builder.py

Sorry about that!  I've got everything in the /Students/ebuer directory now as requested for sessions 01 and 02.  Also getting up to speed on fixing pull request headers -- being out of town can be problematic.  

I noticed in your commands below you used git mv instead of just mv; is this a way to shortcut using mv/git add/git commit?  Just curious. Thanks.