Adding a rough draft of how IPython notebooks for SQL could work.

As I mentioned on the [tutors] listserv I made a rough draft of an IPython notebook based (verbatim) on the first two SWC SQL lessons. The notebook uses the python `SQLite3` module to execute the SQL commands. `SQLite3` uses raw SQL commands so in that sense the lesson material is the same. 

Some people have expressed concern that combining Python with SQL will cause more confusion than it's worth, though other people really like using the IPython notebook. I've taught SQL this way before but I have no way of measuring how much traction I had.

Comments are welcome. If there is interest I could add the remaining lessons.