Merge branch 'doorkeeper_update' into 'master'

Doorkeeper update

https://gitlab.com/gitlab-org/omnibus-gitlab/issues/398

See merge request !1392

Gemfile

@@ -29,7 +29,7 @@ gem 'omniauth-twitter'
 gem 'omniauth-github'
 gem 'omniauth-shibboleth'
 gem 'omniauth-kerberos'
-gem 'doorkeeper', '2.0.1'
+gem 'doorkeeper', '2.1.0'
 gem "rack-oauth2", "~> 1.0.5"
 
 # Browser detection

Gemfile.lock

@@ -109,7 +109,7 @@ GEM
     diff-lcs (1.2.5)
     diffy (3.0.3)
     docile (1.1.5)
-    doorkeeper (2.0.1)
+    doorkeeper (2.1.0)
       railties (>= 3.1)
     dotenv (0.9.0)
     dropzonejs-rails (0.4.14)
@@ -633,7 +633,7 @@ DEPENDENCIES
   devise (= 3.2.4)
   devise-async (= 0.9.0)
   diffy (~> 3.0.3)
-  doorkeeper (= 2.0.1)
+  doorkeeper (= 2.1.0)
   dropzonejs-rails
   email_spec
   enumerize