Defconfig, kernel version and debian package build

I have figured out how to use the defconfig feature of the kernel build to manage the "official" ev3dev kernel configuration. Instead of the 2k+ line ```.config``` file, we have a minimal ```arch/arm/configs/ev3dev_defconfig``` that has only the differences from the ARM default configuration. I think this will be much easier to manage.

I also added the ev3dev kernel version so that we can ask people "what kernel version are you running?" and they can ```uname -r``` and tell us.

I also fixed the debian package build script so that it can handle the uImage. For the next release, we can distribute the kernel and modules as a .deb.