Better align default permissions with standard roles

[tobybellwood]

Over the past couple of years, we have noticed an increase in requirements to have permissions altered at the sub-administrator level. we should go through the standard roles:

• Content Editor
• Content Approver
• Site Editor
• Site Builder
  and ensure that they have sufficient permissions to undertake these roles.

We should also publish "personas" with brief role overviews on the community site that align with the permissions.

@barbun has undertaken some work on this for Media permissions in #483 and @paulkilla has added some site config settings in #395