For beginner camera or lens?

Is it better to get nikon d5100 with Nikon AF-S DX Nikkor 55-300mm f/4.5-5.6G ED VR
or
a cheaper camera with a better lens

You can spend less money and get the D3100, but really the D5100 provides the most bang for the buck

The D5100 with its standard (and included) 18-55 mm lens and the 55-300 mm lens will give you a huge range, enabling you to shoot from landscapes, groups, full body, head and shoulders, sports, action and wildlife

A good combination

I think you should pick up a 50mm 1.8 as they will help you tremendously because of the 1.8 aperture.
If you have the money then look into a f/2.8 lens because even thought the 55-300mm covers a wide range it looses quality and sharpness and it won't allow you to shoot in low light because of the tiny aperture (Google aperture if you don't know what I mean). If you don't have any idea what I'm talking about then you won't mind the 55-300mm, its a great lens either way.