Add automated tests

[didriklundberg]

The first sequence of tests, to make sure that the hypervisor works correctly, can be done manually.

Eventually, as we make new versions of the hypervisor for RPi2, we must automate testing in order to cut development time. In order to do this, we need a handy way of restarting the board. Then, we need to modify the files in test/dtest for the RPi2 as needed.

Here's a code example of bare metal reset from code for the RPi2: https://github.com/dwelch67/raspberrypi/tree/master/blinker06
What we would ideally be looking for is some kind of JTAG reset, though. RPi2 only has TRST and not SRST.