Fixes for experiments table issues: Issues #488 and #581.

Author: gsrohde

app/models/experiment.rb

@@ -1,4 +1,5 @@
 class Experiment < ActiveRecord::Base
+  attr_protected []
 
   extend SimpleSearch
 

app/views/layouts/application.html.erb

@@ -178,6 +178,7 @@
                 <li><%= link_to "Citations", citations_path %></li>
                 <li><%= link_to "Covariates", covariates_path %></li>
                 <li><%= link_to "Cultivars", cultivars_path %></li>
+                <li><%= link_to "Experiments", experiments_path %></li>
                 <li><%= link_to "Managements", managements_path %></li>
                 <% if current_user.page_access_level <= 2 %>
                   <li><%= link_to "Methods", methods_path %></li>