label_singular somehow overrides the default "plural" label

[papandreou]

- Do you want to request a feature or report a bug?

bug

- What is the current behavior?

When a field using the list widget has a label_singular defined, the regular label is not displayed when the list has 0 or 2+ items.

- If the current behavior is a bug, please provide the steps to reproduce.

1. Create a new item in the collection
2. Observe that it says "0 foobar"
3. Add a "Foobar" by clicking the Add foobar + button
4. Observe that it says "1 foobar"
5. Add another one
6. Observe that it says "2 foobar"

- What is the expected behavior?

That the label_singular is used only when there is exactly one item, so that it would say "0 foobars" and "2 foobars".

- Please mention your versions where applicable.

Netlify CMS version: 1.8.4
Browser version: Chrome 66.0.3359.181/OSX

- Please link or paste your config.yml below if applicable.

collections:
  -
    name: mycollection
    label: My collection
    folder: thefolder
    slug: "{{id}}"
    create: true
    fields:
      -
        name: 'foobars'
        label: 'Foobars'
        label_singular: 'Foobar'
        widget: 'list'
        fields:
          -
            name: 'foobar'
            label: 'Foobar'
            widget: 'string'