Add audit trail information to library-cms

[ConnorSheremeta]

From #551:

"We would prefer having role-based authentication where we can audit changes"

and from #626 (comment):

add audit trail information and so forth (can take inspiration from Jupiter maybe for some of this, but by using Devise you have lots of guides/examples/solutions from the community you could adopt).

Audit trail information can be done through the paper_trail gem: https://github.com/paper-trail-gem/paper_trail

Might be worth looking into adding paper_trail versioning to "Trackable" devise concern. Also might be useful to have a whodunnit for each revision to a page/layout/snippet (revision details appear to the right in the corresponding edit page.)

[pgwillia]

Had you considered extending the Revisions functionality that is already in CMS?

• https://github.com/shakacode/comfortable-media-surfer/wiki/Revisions

• library-cms/db/schema.rb

  Lines 117 to 123 in ae044d2

  	create_table "comfy_cms_revisions", charset: "utf8mb3", collation: "utf8mb3_general_ci", force: :cascade do |t|
  	t.string "record_type", null: false
  	t.integer "record_id", null: false
  	t.text "data", size: :medium
  	t.datetime "created_at", precision: nil
  	t.index ["record_type", "record_id", "created_at"], name: "index_cms_revisions_on_rtype_and_rid_and_created_at"
  	end

• https://github.com/shakacode/comfortable-media-surfer/tree/master/app/controllers/comfy/admin/cms/revisions

The challenge then is linking a revision to a particular user, if that's what the Web Team wants.