Add back the <all_urls> permission and try submitting for approval

[ushnisha]

Since the google webextensions webstore review process is getting painful, the all_urls permission was removed to see if there were other issues with submission and review/approval.

Now that version 3.0.21 is approved and available, try and add back the all_urls permission and see if the reviewers will accept and approve the extension with this permission; may need to wait for a few days before resubmitting.