Merge pull request linuxkit#3104 from rn/rel_v0.5

Preparation for v0.5 release

Merge pull request linuxkit#3037 from rn/rel_v0.4

Preparation for the v0.4 release

Merge pull request linuxkit#2990 from rn/pre-release

Final preparation for v0.3 release

Merge pull request linuxkit#2885 from rn/release-part1

v0.2 release