add researchers yaml group to stat1003

This adds the new researchers yaml group
to the node. Currently this group only contains
dartar who already has an account (and therefore
his existing include is being removed)

The group is being used to handle access
to the researchdb password (for now), but can
also be used where appropriate for researchers.

Soon, more users can be migrated from stat1003 node
level to this.

The group has been added in I9c63c560f4

Change-Id: Ic0b31593bec0881b6b3c47ae3b2cd04bcf7dd12a