custom gradebook columns: teacher_notes support

refs CNVS-5856, CNVS-6906, CNVS-6475

Test plan:
  This commit lets you mark columns as teacher_notes columns.  The UI
  only supports one teacher_notes column, but this isn't enforced by
  the API.  Create a teacher_notes column using the API.

Change-Id: I1c15082e95ac08b092148f32f3c6906ec2dcef11
Reviewed-on: https://gerrit.instructure.com/28097
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Simon Williams <simon@instructure.com>
QA-Review: Caleb Guanzon <cguanzon@instructure.com>
Product-Review: Cameron Matheson <cameron@instructure.com>

app/controllers/custom_gradebook_columns_api_controller.rb

@@ -69,6 +69,9 @@ class CustomGradebookColumnsApiController < ApplicationController
   #   The position of the column relative to other custom columns
   # @argument column[hidden] [Optional, Boolean]
   #   Hidden columns are not displayed in the gradebook
+  # @argument column[teacher_notes] [Optional, Boolean]
+  #   Set this if the column is created by a teacher.  The gradebook only
+  #   supports one teacher_notes column.
   #
   # @returns Custom Column
   def create

app/models/custom_gradebook_column.rb

@@ -23,7 +23,7 @@ class CustomGradebookColumn < ActiveRecord::Base
   belongs_to :course
   has_many :custom_gradebook_column_data
 
-  attr_accessible :title, :position, :hidden
+  attr_accessible :title, :position, :teacher_notes, :hidden
 
   validates_presence_of :title
   validates_length_of :title, :maximum => maximum_string_length

db/migrate/20131230213011_add_teacher_notes_to_custom_columns.rb

@@ -0,0 +1,13 @@
+class AddTeacherNotesToCustomColumns < ActiveRecord::Migration
+  tag :predeploy
+
+  def self.up
+    add_column :custom_gradebook_columns, :teacher_notes, :boolean,
+      :default => false,
+      :after => :workflow_state
+  end
+
+  def self.down
+    remove_column :custom_gradebook_columns, :teacher_notes
+  end
+end

lib/api/v1/custom_gradebook_column.rb

@@ -20,7 +20,8 @@ module Api::V1::CustomGradebookColumn
   include Api::V1::Json
 
   def custom_gradebook_column_json(column, user, session)
-    json = api_json column, user, session, :only => %w(id title position)
+    json = api_json column, user, session, :only => %w(id title position
+                                                       teacher_notes)
     json[:hidden] = column.hidden?
     json
   end

spec/lib/api/v1/custom_gradebook_column_spec.rb

@@ -14,7 +14,7 @@ describe "Api::V1::CustomGradebookColumn" do
 
   describe "custom_gradebook_column_json" do
     it "works" do
-      json = @col.attributes.slice(*%w(id title position))
+      json = @col.attributes.slice(*%w(id title position teacher_notes))
       json["hidden"] = false
       controller.custom_gradebook_column_json(@col, @teacher, nil).should == json
     end