Update cmdline.rs testing

[jakecorrenti]

We should come up with a better way to test the cmdline argument parsing. RIght now, every time you want to test a new argument combination, you have to worry about which number argument it is in the ever-growing list of them. This definitely isn't scalable and should be re-thought.

[tylerfanelli]

Order does matter within the command line arguments, so I think that test is still relevant. However, it should be possible to write separate tests that don't test for order.

[jakecorrenti]

Order does matter within the command line arguments, so I think that test is still relevant. However, it should be possible to write separate tests that don't test for order.

The order shouldn't matter within the command line arguments after I re-wrote the argument parsing in #39

[tylerfanelli]

My mistake, I forgot about that. Originally the root and data disk ordering for virtio-blk devices mattered.