use same flag and log library as goreleaser

[client9]

godownloader uses golang native flags
goreleaser uses something else.

They should be the same.

[caarlos0]

goreleaser and nfpm are using alecthomas/kingpin :)

[client9]

hi @caarlos0 are you using another library for logging?

[caarlos0]

hi @caarlos0 are you using another library for logging?

apex/log with the cli logger (which gives those nice coloring and stuff)

[client9]

using apex/log -- needs a lot more cleanup/fixups but thats a different issue.
version info is set up now too. Just need to do tagging and linking.