Add Google oauth2

Gemfile

@@ -12,3 +12,5 @@ gem 'jbuilder', '~> 2.0'
 gem 'sdoc', '~> 0.4.0',          group: :doc
 
 gem 'spring',        group: :development
+
+gem 'omniauth-google-oauth2', '~> 0.2.5'

Gemfile.lock

@@ -38,6 +38,9 @@ GEM
     coffee-script-source (1.8.0)
     erubis (2.7.0)
     execjs (2.2.1)
+    faraday (0.9.0)
+      multipart-post (>= 1.2, < 3)
+    hashie (3.3.1)
     hike (1.2.3)
     i18n (0.6.11)
     jbuilder (2.1.3)
@@ -47,11 +50,31 @@ GEM
       railties (>= 3.0, < 5.0)
       thor (>= 0.14, < 2.0)
     json (1.8.1)
+    jwt (1.0.0)
     mail (2.6.1)
       mime-types (>= 1.16, < 3)
     mime-types (2.3)
     minitest (5.4.2)
     multi_json (1.10.1)
+    multi_xml (0.5.5)
+    multipart-post (2.0.0)
+    oauth2 (1.0.0)
+      faraday (>= 0.8, < 0.10)
+      jwt (~> 1.0)
+      multi_json (~> 1.3)
+      multi_xml (~> 0.5)
+      rack (~> 1.2)
+    omniauth (1.2.2)
+      hashie (>= 1.2, < 4)
+      rack (~> 1.0)
+    omniauth-google-oauth2 (0.2.5)
+      omniauth (> 1.0)
+      omniauth-oauth2 (~> 1.1)
+    omniauth-oauth2 (1.2.0)
+      faraday (>= 0.8, < 0.10)
+      multi_json (~> 1.3)
+      oauth2 (~> 1.0)
+      omniauth (~> 1.2)
     rack (1.5.2)
     rack-test (0.6.2)
       rack (>= 1.0)
@@ -111,6 +134,7 @@ DEPENDENCIES
   coffee-rails (~> 4.0.0)
   jbuilder (~> 2.0)
   jquery-rails
+  omniauth-google-oauth2 (~> 0.2.5)
   rails (= 4.1.6)
   sass-rails (~> 4.0.3)
   sdoc (~> 0.4.0)

config/initializers/omniauth.rb

@@ -0,0 +1,14 @@
+OmniAuth.config.logger = Rails.logger
+
+Rails.application.config.middleware.use OmniAuth::Builder do
+  provider :google_oauth2,
+    Rails.application.secrets.google_client_id,
+    Rails.application.secrets.google_client_secret,
+    {
+      client_options: {
+        ssl: {
+          ca_file: Rails.root.join('cacert.pem').to_s
+        }
+      }
+    }
+end