Fix the issue of Resouces.getXml(int)
Fix the issue that Resources.getXml(int) does not support resource ids other than xml resources. According to original (Android SDK's) implementation, it should support not only xml resources, but also other resources whose file types are xml - e.g. layout, menu, drawable, anim and color. Test cases have been added accordingly.
Added xml root tag verification to Resouces.getXml(int) test cases.
Removed unused import
Merge pull request #636 from thorikawa/fix_resources_getxml

Fix the issue of Resouces.getXml(int)