Update Nokogiri

Solves the latest security vulnerability

Gemfile.lock

@@ -92,7 +92,7 @@ GEM
       execjs
     coffee-script-source (1.12.2)
     columnize (0.8.9)
-    concurrent-ruby (1.0.3)
+    concurrent-ruby (1.0.5)
     connection_pool (2.2.0)
     crack (0.4.3)
       safe_yaml (~> 1.0.0)
@@ -135,7 +135,7 @@ GEM
     high_voltage (3.0.0)
     http-cookie (1.0.3)
       domain_name (~> 0.5)
-    i18n (0.7.0)
+    i18n (0.8.1)
     inifile (3.0.0)
     jquery-rails (4.2.1)
       rails-dom-testing (>= 1, < 3)
@@ -170,7 +170,7 @@ GEM
       thor (~> 0.19)
     netrc (0.11.0)
     nio4r (1.2.1)
-    nokogiri (1.6.8.1)
+    nokogiri (1.7.1)
       mini_portile2 (~> 2.1.0)
     normalize-rails (3.0.3)
     oauth2 (1.2.0)
@@ -216,9 +216,9 @@ GEM
     rails-assets-classnames (2.2.5)
     rails-assets-es5-shim (4.5.9)
     rails-assets-lodash (4.13.1)
-    rails-dom-testing (2.0.1)
+    rails-dom-testing (2.0.2)
       activesupport (>= 4.2.0, < 6.0)
-      nokogiri (~> 1.6.0)
+      nokogiri (~> 1.6)
     rails-html-sanitizer (1.0.3)
       loofah (~> 2.0)
     rails_12factor (0.0.2)
@@ -318,7 +318,7 @@ GEM
     stripe (1.57.1)
       rest-client (>= 1.4, < 4.0)
     thor (0.19.1)
-    thread_safe (0.3.5)
+    thread_safe (0.3.6)
     tilt (2.0.5)
     tzinfo (1.2.2)
       thread_safe (~> 0.1)