adding tests for compute_streak
Adding one test with current and longest streak, fixing the current streak logic
Fixing negative index
Merge pull request #35 from bkendall/streak-tests

Little contribution to your streak-tests branch
wrote tests with expected behavior for only 1 day streaks and 0 runs
Fixing current streak and longest streak for short lists
Merge pull request #36 from bkendall/streak-tests

Fixing current streak and longest streak for short lists