change to idiomatic use of layouts versus regular views

no functional change here, but familiar Rails users will see view files in the
locations they expect. this also slightly simplifies controller code

there is one attendant change in the wiki at `rails_3/A1-SQL-Injection-Interpolation.md`
that I'm happy to make after the PR is merged.

app/controllers/admin_controller.rb

@@ -17,19 +17,18 @@ class AdminController < ApplicationController
     else
       @analytics = Analytics.all
     end
-    render "layouts/admin/_analytics"
   end
 
   def get_all_users
     @users = User.all
-    render :partial => "layouts/admin/get_all_users"
+    render layout: false
   end
 
   def get_user
     @user = User.find_by_id(params[:admin_id].to_s)
     arr = ["true", "false"]
     @admin_select = @user.admin ? arr : arr.reverse
-    render :partial => "layouts/admin/get_user"
+    render layout: false
   end
 
   def update_user

app/controllers/dashboard_controller.rb

@@ -15,12 +15,12 @@ class DashboardController < ApplicationController
   end
 
   def bar_graph
-    render :partial => "layouts/dashboard/bar_graph"
+    render :bar_graph, layout: false
   end
 
   def pie_charts
      @user = current_user
-     render :partial => "layouts/dashboard/dashboard_stats"
+     render :dashboard_stats, layout: false
   end
 
 end

app/controllers/tutorials_controller.rb

@@ -3,7 +3,7 @@ class TutorialsController < ApplicationController
   skip_before_action :authenticated
 
   def credentials
-    render :partial => "layouts/tutorial/credentials/creds"
+    render layout: false
   end
 
 end