Release 0.5.0 (or 0.4.1)

[kolyshkin]

Can we please merge #36 and release v0.4.1 (or v.0.5.0)?

Commits since v0.4.0 (at the moment this is just PR #40): v0.4.0...master

[kolyshkin]

@thaJeztah PTAL (or do you think there is something else needed to be done for the next release? If yes, I am happy to help)

[thaJeztah]

I pushed v0.5.0 https://github.com/docker/go-units/releases/tag/v0.5.0