Fix `roDeviceInfo` method typo and some test cases

[lvcabral]

• The method getAudioDecodeInfo was wrongly spelled, and getSupportedGraphicsResolutions was returning an AA when the correct is a roArray.
• Skipped one roXMLElement test case that is not behaving as Roku, the implementation is wrong, to be fixed later when roXMLList is implemented.
• Renamed Timespan.test.js to RoTimeSpan.test.js to match the standard of other tests