Keep old work

In assignments/session04 I am submitting instructions, my app and tests.

Contrary to the assignment's instructions, my app does not incorporate my web scraper from last week. I really didn't understand how the tests in books app were working, and wanted to spend some time on that this week. 

Also I was hoping to figure out the git cleanup, but got stuck (see email I sent the group). Apologies for the extra stuff in this pull request.