Lab2

Here are my suggested edits to lab2. After talking to the TAs and students in the class, we decided that timing things was too complicated for a beginning lab (not to mention that it isn't part of this lab's objective), so we removed those problems. The plan is to include timing in the profiling lab.
Good description here for what the two libraries are used for. Before, it was never really clear why we cared about SciPy.