feat(version): Add JSON/YAML output formats for version command

[navidshaikh]

Fixes #513

Description:

Add -o flag to kn version command and support JSON/YAML formats.

Changes

Examples:

➜  client git:(pr/kn-version-json) kn version -ojson
{
	"Version": "v20200309-local-1cbb94e2-dirty",
	"BuildDate": "2020-03-09 13:35:39",
	"GitRevision": "1cbb94e2",
	"SupportedAPIs": {
		"eventing": [
			"sources.eventing.knative.dev/v1alpha1 (knative-eventing v0.13.1)",
			"sources.eventing.knative.dev/v1alpha2 (knative-eventing v0.13.1)",
			"eventing.knative.dev/v1alpha1 (knative-eventing v0.13.1)"
		],
		"serving": [
			"serving.knative.dev/v1 (knative-serving v0.13.0)"
		]
	}
}

and

➜  client git:(pr/kn-version-json) kn version -oyaml
BuildDate: "2020-03-09 13:35:39"
GitRevision: 1cbb94e2
SupportedAPIs:
  eventing:
  - sources.eventing.knative.dev/v1alpha1 (knative-eventing v0.13.1)
  - sources.eventing.knative.dev/v1alpha2 (knative-eventing v0.13.1)
  - eventing.knative.dev/v1alpha1 (knative-eventing v0.13.1)
  serving:
  - serving.knative.dev/v1 (knative-serving v0.13.0)
Version: v20200309-local-1cbb94e2-dirty

/lint

[knative-prow-robot]

@navidshaikh: 1 warning.

In response to this:

Fixes #513

Description:

Add -o flag to kn version command and support JSON/YAML formats.

Changes

Examples:

➜  client git:(pr/kn-version-json) kn version -ojson
{
  "Version": "v20200309-local-1cbb94e2-dirty",
  "BuildDate": "2020-03-09 13:35:39",
  "GitRevision": "1cbb94e2",
  "SupportedAPIs": {
  	"eventing": [
  		"sources.eventing.knative.dev/v1alpha1 (knative-eventing v0.13.1)",
  		"sources.eventing.knative.dev/v1alpha2 (knative-eventing v0.13.1)",
  		"eventing.knative.dev/v1alpha1 (knative-eventing v0.13.1)"
  	],
  	"serving": [
  		"serving.knative.dev/v1 (knative-serving v0.13.0)"
  	]
  }
}

and

➜  client git:(pr/kn-version-json) kn version -oyaml
BuildDate: "2020-03-09 13:35:39"
GitRevision: 1cbb94e2
SupportedAPIs:
 eventing:
 - sources.eventing.knative.dev/v1alpha1 (knative-eventing v0.13.1)
 - sources.eventing.knative.dev/v1alpha2 (knative-eventing v0.13.1)
 - eventing.knative.dev/v1alpha1 (knative-eventing v0.13.1)
 serving:
 - serving.knative.dev/v1 (knative-serving v0.13.0)
Version: v20200309-local-1cbb94e2-dirty

/lint

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[knative-prow-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: navidshaikh

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[navidshaikh]

/cc: @joshuawilson

[joshuawilson]

That looks good. What will be different when the version is a released version instead of a local build?

[navidshaikh]

@joshuawilson:
If its a local build, we get:

	"Version": "v20200309-local-1d4b497b",

while for released build:

	"Version": "v0.13.0",

rest of the fields should stay intact

[joshuawilson]

Thanks for fixing this.
Do you want me to mark/tag anything?

[navidshaikh]

@joshuawilson thanks for the review!

/assign @rhuss

[rhuss]

Looks good to me with some a minor improvement suggestion.

@navidshaikh do you want to address that now or ok to do it post 0.13.0 ?

[knative-metrics-robot]

The following is the coverage report on the affected files.
Say /test pull-knative-client-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/kn/commands/version/version.go	100.0%	93.5%	-6.5

[rhuss]

/lgtm

[navidshaikh]

@rhuss: addressed the review comment.