Fixed some minor typos, made other small changes to the scipy.optimize
lab.
Fixed another little error.
Changed 'optimization' to 'optimize' where appropriate, specified x0 in
the second problem, put a negative sign in Newton's law of cooling, fixed
the solution tester for problem 3, removed the extraneous third column in
heating.txt.
Merge pull request #442 from abefrandsen/scipyOptimize

Several small edits to the scipy.optimize lab.