Exit nonzero from run_tests.sh if any tests failed
Fail rake test task if test script fails
Refactor tests so order doesn't matter
Fix spurious failing test cases
Merge branch 'test_failure_status' of https://github.com/MicahChalmer/timecop into MicahChalmer-test_failure_status

* 'test_failure_status' of https://github.com/MicahChalmer/timecop:
  Fix spurious failing test cases
  Refactor tests so order doesn't matter
  Fail rake test task if test script fails
  Exit nonzero from run_tests.sh if any tests failed