Digital comms from private repo

Add digital comms from private repo

Updated styling for guide nav

Add staff info index

Update staff changes page styling

Add downloads page

Restrict staff info image widths

Set prison_staff_info version lock to master

Enable IP restriction on staff portal

Specs for Staff portal
Merge pull request #27 from ministryofjustice/feature/digital-comms

Digital comms for the staff.

[Finishes #1311826]