Perftool new

Changes:

* `api.getDownloadURLs` has changed to `api.getDownloads`
* `api.getPerfmon` has changed to `api.getPerfMon`
* `scenarioObject._scnId` has changed to `scenarioObject.scnId`
* added performance test api `api.getPerformanceTest`, `api.getPerformanceTestReports`, `api.runPerformanceTest`
* improved documentation
* added an example