Support more platforms

[NHellFire]

Currently only x86 and PPC are supported. It'd be good to support other platforms such as ARM.
As I don't have a system to test on, I'd need either donations to buy one or people to build one and submit patches (should just be buildroot and kernel configs).

Additional work needed:

• Per arch buildroot and kernel configs
• Update scripts (master.sh / environment.sh) to ask for arch. Could just detect from buildroot/.config
• PPC needs us to build yaboot (or u-boot should work)
• Find bootloader for ARM.. possibly u-boot?

[Firminator]

What about a Raspberry Pi? I'll send you one.

U-Boot docs: https://www.denx.de/wiki/DULG/Manual