Add rerunFailingTestsCount option for maven surefire to rerun failing tests immediately after they fail.

When rerunFailingTestsCount is set to a value larger k than 0, a failing test will get re-run
up to k times until it passes. If a test passes in any of its reruns,
the build will be marked as successful and the test will count as a
flake (or flaky test). If it fails all those k times then it will
still be marked as a failed test.

In the console output all the flaky tests will be count as "Flakes:
N". The generated test report XML file is augmented with additional
information, while still being compatible with existing consumers
(such as Jenkins). A flaky test will have <flakyFailure> or/and
<flakyError> under its <testcase> element, to store all the flaky
runs' information (such as output, stackTrace). So existing consumers
will still consider it as a passing test, while potential future
consumers can parse those flaky runs information. A failing test will
still have <failure> or <error> under <testcase>, but all the
subsequent re-run information will be stored under <rerunFailure> or
<rerunError>. So existing consumers will still be able to see it's a
failed test and parse its failure information, and potential future
consumers will be able to get all the flaky runs.

It is implemented by keeping a map between test full class name and a
map between all its test methods and the list of runs. It also takes
into account Fork and Parallel and have them covered by integration
tests.

Currently only supports JUnit4.x
Adjust example page for rerun failing tests to be valid for surefire and failsafe plugin