Description of problem:

When using a label with a / in it in buildconfig, it throws an error like below:

"The BuildConfig "cpd-cli" is invalid: spec.output.imageLabels[0].name: Invalid value: "app.kubernetes.io/part-of": a valid config key must consist of alphanumeric characters, '-', '_' or '.' (e.g. 'key.name',  or 'KEY_NAME',  or 'key-name', regex used for validation is '[-._a-zA-Z0-9]+')"

Version-Release number of selected component (if applicable):
4.8

How reproducible:
Always

Steps to Reproduce:
1. Create a buildconfig manifest having 'imageLabels:' option and the label name  having a / in it like below:

    imageLabels:
      - name: app.kubernetes.io/part-of
        value: customized-app
2. Try to create the buildconfig using 'oc create -f <file-name>'
3. It throws the mentioned error and does't allow a label with / in it

Actual results:
Getting the mentioned error when trying to use a label with / in it

Expected results:
The buildconfig should get created without any error. It should accept a label with /.

Additional info: