Please use 64-bit key IDs

[jepler]

Please see https://evil32.com/ (note: site will not damage your computer :-P) for why it is important to begin using key IDs bigger than 32 bits.

I notice that in documentation such as docs/getting-started/APT-packages-raspbian.asciidoc 32-bit key IDs are being used.

As far as I understand it, gpg and apt-key adv will both know how to use 64-bit key IDs, but I haven't verified this.

While I'm asking, is this the proper key?

pub   2048R/31B5958F43DDF224 2016-02-28
uid                          Machinekit Signer <[email protected]>
sub   2048R/9AF25B185CFD4136 2016-02-28
sub   2048D/F81BD2B7499BE968 2016-02-29