update xml lib on top of mongo changes

Gemfile

@@ -30,7 +30,7 @@ gem 'mongoid_magic_counter_cache'
 gem 'faker'
 gem 'will_paginate_mongoid', "~>2.0"
 gem 'rdiscount'
-gem 'nokogiri'
+gem 'nokogiri', "~>1.6.7.1"
 
 gem 'tire', "0.6.2"
 gem 'tire-contrib'

Gemfile.lock

@@ -77,6 +77,7 @@ GEM
     listen (0.5.0)
     method_source (0.8)
     mime-types (2.6.1)
+    mini_portile2 (2.0.0)
     minitest (5.8.1)
     mongo (2.1.1)
       bson (~> 3.0)
@@ -94,7 +95,8 @@ GEM
     multi_json (1.11.2)
     netrc (0.10.3)
     newrelic_rpm (3.13.2.302)
-    nokogiri (1.5.5)
+    nokogiri (1.6.7.1)
+      mini_portile2 (~> 2.0.0.rc2)
     origin (2.1.1)
     protected_attributes (1.1.3)
       activemodel (>= 4.0.1, < 5.0)
@@ -185,7 +187,7 @@ DEPENDENCIES
   mongoid-tree!
   mongoid_magic_counter_cache
   newrelic_rpm
-  nokogiri
+  nokogiri (~> 1.6.7.1)
   protected_attributes
   pry
   pry-nav