UI for adding SIS token to canvas

fixes SIS-641

Test plan:
- generate a token in SIS App
- copy and paste the token in the 'SIS Token Authentication' field
-- you must enable the Post Grades to SIS feature to see this setting
- update the settings and confirm the sis token was saved

Change-Id: I13f2e0136809c42d7b7c7b30c330efb11f6dc29f
Reviewed-on: https://gerrit.instructure.com/44358
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Tyler Pickett <tpickett+gerrit@instructure.com>
QA-Review: Jeremy Putnam <jeremyp@instructure.com>
Product-Review: Nick Houle <nhoule@instructure.com>

app/models/account.rb

@@ -162,6 +162,7 @@ class Account < ActiveRecord::Base
 
   # these settings either are or could be easily added to
   # the account settings page
+  add_setting :sis_app_token, :root_only => true
   add_setting :global_includes, :root_only => true, :boolean => true, :default => false
   add_setting :global_javascript, :condition => :allow_global_includes
   add_setting :global_stylesheet, :condition => :allow_global_includes

app/views/accounts/settings.html.erb

@@ -366,6 +366,24 @@ TEXT
           <% end %>
         </fieldset>
 
+        <% if !@account.site_admin? &&
+                @account.root_account? &&
+                @account.feature_enabled?(:post_grades) &&
+                @account.grants_right?(@current_user, :manage_site_settings) %>
+            <fieldset id="add_sis_app_token">
+              <legend><%= t("SIS Token Authentication") %></legend>
+              <p style="font-size: 0.9em;"><%= t("This will allow you to authenticate Canvas for posting grades to SIS") %></p>
+              <%= f.fields_for :settings do |settings| %>
+                  <table class="formtable">
+                    <tr>
+                      <td><%= settings.blabel :sis_app_token, :en => "SIS Token" %></td>
+                      <td><%= settings.text_field :sis_app_token, :value => @account.settings[:sis_app_token] %></td>
+                    </tr>
+                  </table>
+              <% end %>
+            </fieldset>
+        <% end %>
+
         <% if @account.root_account? && !@account.site_admin? && Setting.get("show_feedback_link", "false") == "true"  %>
           <fieldset>
             <legend><%= t(:custom_links_to_include_in_the_help_dialog_popup, "Custom Links to include in the help dialog popup") %></legend>