Feature/enable retries

[steph-lebl]

Fix for #53

These new features are used to improve mocha-concurrent-api-tests and provide a detail for flaky tests in the test report.
For more details see:
https://github.com/VilledeMontreal/mocha-concurrent-api-tests/blob/master/example/README.md#test-report-exemple-when-a-test-fails-or-does-not-succeed-on-the-first-time-flaky

/**

• If a test fails, it will be retried until it succeeds or maxRetries is reached.
• Useful if some tests have dependecies (ex: network) that fail from time to time.
• @param {int} n
  */
  parallel.maxRetries(n)

/**

• If a test hang and maxRetries > 0, the test will be retried after retryTimeoutInMiliseconds
• retryTimeoutInMiliseconds does not alter the default timeout of Mocha.
• Ex:
• if a test hang forever and maxRetries=10, retryTimeoutInMiliseconds=1000 and
• mocha timeout is 5 secondes, then the test will be retried 5 times because
• retryTimeoutInMiliseconds but will stop as soon as Mocha timeout is readed.
• @param {int} n
  */
  parallel.retryTimeoutInMiliseconds(n)

/**

• getRetriedTestFailures allow to know what caused the test to be retried.
• maxRetries avoid failling the suite because of some flaky tests but flaky
• tests should not be retried silently.
• getRetriedTestFailures can be used to include retried test failures in
• a custom Mocha reporter.
• For more details, see https://mochajs.org/api/tutorial-custom-reporter.html
  */
  parallel.getRetriedTestFailures()