automatically re-run tests that failed

Unfortunately, like all test suites, ours has some flaky tests that fail
non-deterministically and have been very difficult to fix. A typical
solution is to re-try the tests that failed the first time. This issue
covers adding that to our test suite.

Xref
http://stackoverflow.com/questions/13547175/how-to-rerun-the-failed-tests-with-ctest