bump verion to v2

[dylanhitt]

Fixes #166

It appears with the introduction of go modules you're required to version in go.mod. The guys over at golang/go do a way better job explaining this than I will.

The following works:

$ docker run -it golang:1.16 bash
root@6b1de3212ce1:/go# go get github.com/commander-cli/commander/v2/cmd/commander@bump-go-mod-version 
go: downloading github.com/commander-cli/commander/v2 v2.4.1-0.20210409193347-b7852b522732
go: downloading github.com/urfave/cli v1.22.5
go: downloading github.com/commander-cli/cmd v1.3.0
go: downloading gopkg.in/yaml.v2 v2.4.0
go: downloading github.com/logrusorgru/aurora v2.0.3+incompatible
go: downloading github.com/docker/docker v1.13.1
go: downloading golang.org/x/crypto v0.0.0-20210322153248-0c34fe9e7dc2
go: downloading github.com/antchfx/xmlquery v1.3.5
go: downloading github.com/pmezard/go-difflib v1.0.0
go: downloading github.com/tidwall/gjson v1.7.1
go: downloading github.com/stretchr/testify v1.7.0
go: downloading github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d
go: downloading github.com/antchfx/xpath v1.1.10
go: downloading github.com/golang/groupcache v0.0.0-20200121045136-8c9f03a8e57e
go: downloading golang.org/x/net v0.0.0-20210226172049-e18ecbb05110
go: downloading github.com/tidwall/match v1.0.3
go: downloading github.com/tidwall/pretty v1.1.0
go: downloading github.com/davecgh/go-spew v1.1.1
go: downloading gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c
go: downloading github.com/russross/blackfriday/v2 v2.0.1
go: downloading golang.org/x/text v0.3.3
go: downloading github.com/docker/go-connections v0.4.0
go: downloading github.com/docker/go-units v0.4.0
go: downloading golang.org/x/sys v0.0.0-20201119102817-f84b799fce68
go: downloading github.com/docker/distribution v2.7.1+incompatible
go: downloading github.com/pkg/errors v0.9.1
go: downloading github.com/shurcooL/sanitized_anchor_name v1.0.0
go: downloading github.com/opencontainers/go-digest v1.0.0
go: downloading github.com/Microsoft/go-winio v0.4.16
root@6b1de3212ce1:/go#

I'm unsure if this will require any other changes such as our badges?? Or really anything for that matter.

[SimonBaeumer]

Nice thank you!
Imho you can rebase and merge it :)