0.5.0_pre3: Merge pull request #38 from smoser/fix/load-modules-fix

Changes since 0.5.0-pre2:

• Linux kernel 5.3.0-26.28~18.04.1 for aarch64, arm, i386, ppc64le, x86_64
• grub 2.02-2ubuntu8.14 for same archs as above
• powerpc and ppc64 targets uses older kernel/grub as they are not supported by Ubuntu 18.04
• VirtIO RNG support got added to images and test script
• some changes to module loading
  • no more 'no kernel module found' messages
  • printing list of loaded modules
• documentation got improved a bit