So basicly, running 'abuild-keygen -a -i' will be all you need to do to
be able to use abuild-sign and install the signed packages.

we can only sign indexes so far

- ability to embed an checksum inside the tar header for regular
  files (to avoid checksumming at apk installation time)
- way to remove the end-of-archive marker to create concenatable
  .tar.gz:s for signed apks

the modloop will need loop and cramfs modules. Those are only available
in initramfs stage so we must make sure they are properly loaded.

otherwise will awk not detect empty fields

saves us for lots of headache.

seems like copy removes destination if source does not exist so
we ended up with a buildrepo that removed all packages

abuild will not consider package up2date unless apk cache is up2date