MediaRouter: Make sStatic.mResources store application resources.

Previously it stored system resources, and that caused
Resources.NotFoundException in following methods:
 - RouteInfo.getName()
 - RouteCategory.getName()
 - UserRouteInfo.setIconResource(int)
 - RouteGroup.setIconResource(int)
Also, this CL makes getName()/setName() methods work properly.

Bug: 30797944
Test: run a simple app that calls above methods.
Change-Id: Ia5db57c3d7b71c91dcfeea0584867ee2d846fef9