switch to fork of nokogiri

This is required for ratom until this PR is merged sparklemotion/nokogiri#1327

refs CNVS-22298

Change-Id: If99e10659b5b17e8cc8e0df49fbf5ba1214b8612
Reviewed-on: https://gerrit.instructure.com/59948
Reviewed-by: Cody Cutrer <cody@instructure.com>
Tested-by: Jenkins
QA-Review: August Thornton <august@instructure.com>
Product-Review: Brian Palmer <brianp@instructure.com>

Gemfile.d/app.rb

@@ -62,7 +62,7 @@
   gem 'subexec', '0.0.4', require: false
 gem 'multi_json', '1.10.1'
 gem 'netaddr', '1.5.0', require: false
-gem 'nokogiri', '1.6.6.2', require: false
+gem 'nokogiri', '1.6.6.2.20150804122945', require: false, github: 'codekitchen/nokogiri', ref: '6462d9c3ee'
 # oauth gem, with rails3 fixes rolled in
 gem 'oauth-instructure', '0.4.10', require: false
 gem 'oauth2', '1.0.0', require: false