✨ bump CR to v0.4.0 and CT to v0.2.4

[mengqiy]

Preparation for releasing KB v2.2.0.
I have ensured the tutorials under book can still build. I have make necessary changes to go.mod in the tutorials.

Changes regarding installation will be done after the release is out.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: mengqiy

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [mengqiy]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[k8s-ci-robot]

New changes are detected. LGTM label has been removed.

[mengqiy]

hmm...
It seems we have a problem with k8s 1.14
Travis is failing consistently on 1.14
See: https://travis-ci.org/kubernetes-sigs/kubebuilder/builds/612651769?utm_medium=notification&utm_source=github_status and https://travis-ci.org/kubernetes-sigs/kubebuilder/builds/612638752?utm_medium=notification&utm_source=github_status

[mengqiy]

I will try to debug it later tonight.

[k8s-ci-robot]

New changes are detected. LGTM label has been removed.

[k8s-ci-robot]

@mengqiy: The following tests failed, say /retest to rerun them all:

Test name	Commit	Details	Rerun command
pull-kubebuilder-e2e	b2376f6	link	/test pull-kubebuilder-e2e
pull-kubebuilder-test	b2376f6	link	/test pull-kubebuilder-test

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository. I understand the commands that are listed here.