Solve question 9
Update README
Solve question 11
Implement recursive solution for question 11 as well
Solve question 12
Use py.test and tox to run tests
Add python 3 support and testing
Normalize filenames, test class names, and add utf8 header where missing
Solve question 13
Solve question 14
Improve question 14 solution
Solve question 15
Fix tests to just call assertEqual rather than unnecessarily type-specific methods e.g. assertSetEqual
Move solutions into 'solutions' dir to avoid cluttery repo front page
Solve question 16
Solve question 18
Solve question 19
Solve question 21
Remove spurious line in ContrivedQueue