This simplifies setup by remove the unneeded RAM voltage checking.

According to the spec, DDR3L RAM has to work using 1.5V, see
https://en.wikipedia.org/wiki/DDR3_SDRAM#DDR3L_and_DDR3U_extensions.
Coreboot simply doesn't always implement changing voltage, which
can never prevent RAM from working though.

Closes #50
Fixes #38

also, we use the check for x230 in the flashing scripts now. They have
to be run as root now.

Now our scripts start with _where_ it should be run. x230_*.sh should
be run on the x230 where Skulls should be installed. external_*.sh
obviously not.

This also adds the -f <flasher> option and an interactive menu if not
specified.