Added support for versioning of layout test results of run-webkit-tests runs.
And to generate a dashboard of all archived layout test results.

On local runs of run-webkit-tests, the results are overwritten. If required, we cannot refer to the older
generated which might be required many times.
Instead we can archive the results by adding a time-stamp
to the folder name on each run which will help us track the change in results with each iteration of results run.

And also we can generate a dashboard out of all the archived results to validate each individual test over many iterations of testing.

BUG=305508

Review URL: https://codereview.chromium.org/339623002

git-svn-id: svn://svn.chromium.org/blink/trunk@179332 bbb929c8-8fbe-4397-9dbb-9b2b20218538