Allow admin to create new user identities

app/controllers/admin/identities_controller.rb

 class Admin::IdentitiesController < Admin::ApplicationController
   before_action :user
-  before_action :identity, except: :index
+  before_action :identity, except: [:index, :new, :create]
+
+  def new
+    @identity = Identity.new
+  end
+
+  def create
+    @identity = Identity.new(identity_params)
+    @identity.user_id = user.id
+
+    if @identity.save
+      redirect_to admin_user_identities_path(@user), notice: 'User identity was successfully created.'
+    else
+      render :new
+    end
+  end
 
   def index
     @identities = @user.identities

app/views/admin/identities/index.html.haml

 - page_title "Identities", @user.name, "Users"
 = render 'admin/users/head'
 
+= link_to 'New Identity', new_admin_user_identity_path, class: 'pull-right btn btn-new'
 - if @identities.present?
   .table-holder
     %table.table

app/views/admin/identities/new.html.haml

+- page_title "New Identity"
+%h3.page-title New identity
+%hr
+= render 'form'

config/routes.rb

@@ -188,7 +188,7 @@ Rails.application.routes.draw do
   namespace :admin do
     resources :users, constraints: { id: /[a-zA-Z.\/0-9_\-]+/ } do
       resources :keys, only: [:show, :destroy]
-      resources :identities, only: [:index, :edit, :update, :destroy]
+      resources :identities, except: [:show]
 
       delete 'stop_impersonation' => 'impersonation#destroy', on: :collection