Return CI entry config as value by default

lib/gitlab/ci/config/node/entry.rb

@@ -9,7 +9,8 @@ module Gitlab
           class InvalidError < StandardError; end
 
           attr_reader :config
-          attr_accessor :key, :description
+          attr_accessor :description
+          attr_writer :key
 
           def initialize(config)
             @config = config
@@ -48,7 +49,7 @@ module Gitlab
           end
 
           def value
-            raise NotImplementedError
+            @config
           end
 
           def self.nodes

lib/gitlab/ci/config/node/image.rb

@@ -11,10 +11,6 @@ module Gitlab
           validations do
             validates :config, type: String
           end
-
-          def value
-            @config
-          end
         end
       end
     end

lib/gitlab/ci/config/node/script.rb

@@ -11,10 +11,6 @@ module Gitlab
           validations do
             validates :config, array_of_strings: true
           end
-
-          def value
-            @config
-          end
         end
       end
     end

lib/gitlab/ci/config/node/services.rb

@@ -11,10 +11,6 @@ module Gitlab
           validations do
             validates :config, array_of_strings: true
           end
-
-          def value
-            @config
-          end
         end
       end
     end