Add a test freshness page.

Add a test freshness page.
https://bugs.webkit.org/show_bug.cgi?id=180126

Reviewed by Ryosuke Niwa.

Added a page to show freshness of a test.
The test freshness page reports on the same set of tests as the one shown in the summary page.
Use a logistic function to evaluate the freshness of the data points.
This function has the desired property which increase dramatically when it close to the center of the graph.
'acceptableLastDataPointDurationInHour' configs the center of the graph.

* public/include/manifest-generator.php:
* public/v3/components/freshness-indicator.js: Added.
(FreshnessIndicator): A cell of the test freshness table, color will transit from green to red.
(FreshnessIndicator.prototype.update): Update the the data point information and triggers
the cell to re-render if anything changes.
(FreshnessIndicator.prototype._renderIndicator): Re-render the indicator.
(FreshnessIndicator.prototype.render): Render the box color base on a logistic function.
(FreshnessIndicator.prototype._createIndicator):
(FreshnessIndicator.htmlTemplate):
(FreshnessIndicator.cssTemplate):
* public/v3/index.html:
* public/v3/main.js: Added test freshness page.
(main):
* public/v3/models/build-request.js: Refactored waitingTime function to make it reusable.
(BuildRequest.formatTimeInterval): Format time interval in million seconds to more user friendly text.
(BuildRequest.prototype.waitingTime):
* public/v3/pages/test-freshness-page.js: Added.
(TestFreshnessPage):
(TestFreshnessPage.prototype.name):
(TestFreshnessPage.prototype._loadConfig): Load config from summary page configurations.
(TestFreshnessPage.prototype.open):
(TestFreshnessPage.prototype._fetchTestResults):
(TestFreshnessPage.prototype.render):
(TestFreshnessPage.prototype._renderTable):
(TestFreshnessPage.prototype._isValidPlatformMetricCombination): Return whether a platform
and metric combination is valid.
(TestFreshnessPage.prototype._constructTableCell):
(TestFreshnessPage.cssTemplate):
(TestFreshnessPage.prototype.routeName):
* server-tests/api-manifest-tests.js: Added 'warningHourBaseline' so that we can config the
parameter of logistic funciton.
* unit-tests/build-request-tests.js: Added unit tests for formatTimeInterval.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@225898 268f45cc-cd09-0410-ab3c-d52691b4dbfc