Make get_kernels return kernels in some order of creation

[eatonphil]

It seems like the kernels are just returned in a random order. It would be nicer if they were returned in either created order or the reverse so you could just pull [0] or [-1] to get the latest.

[Dorthu]

I believe this library lists objects in the order the api returns them. You can use the order_by filter to ask the api to sort objects differently.