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/views/dashboard/home.html.erb

@@ -21,7 +21,7 @@
 				  <!-- End Title Buttons-->
 			    </div>
 			    <div id="charts_body" class="widget-body">
-				      <%#= render :partial => "layouts/dashboard/dashboard_stats"%>
+				      <%#= render partial: "dashboard_stats" %>
 			    </div>
 				<div class="clearfix">
 		        </div>